replacing all ifndef with pargma once

All the kernel header files now use pargma once rather than the ifndef,
as the pre-processed C files do not change while header files
are protected with pargma once. This will also solve any naming issues
caused by ifndef.

Convert license tags to SPDX identifiers

This commit also converts our own copyright headers to directly use
SPDX, but leaves all other copyright header intact, only adding the
SPDX ident. As far as possible this commit also merges multiple
Data61 copyright statements/headers into one for consistency.

trivial: remove duplicate macro definition

Create device untypeds at boot for all arches

Currently on x86 device untypeds are generated by passing the entire
address space minus any parts that are reserved by the kernel or that
are "real" memory (e.g. kernel image, physical RAM).

On ARM and RISC-V, device untypeds were generated at compile-time from
a device tree. This patch moves ARM and RISC-V to use the same approach
as x86, and moves the code from x86 into a common location that's
shared between the three architectures.

Co-Authored-By: Anna Lyons <anna@gh.st>

mcs: Add a scheduling context object

This is the first part of the seL4 MCS. This commit:

* adds a scheduling context object. Threads without scheduling
context objects cannot be scheduled.
* replaces tcbTimeSlice with the scheduling context object
* adds seL4_SchedControl caps for each core
* adds seL4_SchedControl_Configure which allows users to configure
amount of ticks a scheduling context has, and set a core for the
scheduling context.
* adds seL4_SchedContext_Bind, Unbind and UnbindObject, which allows
a tcb to be bound to a scheduling context.

ARM boot: add MODE_RESERVED to MAX_NUM_FREEMEM_REG

This accounts for the ASID PD hole splitting the main memory region.

boot: allocate rootserver objects last

This change allows us to know, from just the kernel and dtb, where user
level untyped objects start being allocated from.

- allocate rootserver objects from last available freemem region.
- move create_rootserver_objects call into init_freemem.

ARM boot: MAX_NUM_FREEMEM_REG++ for new allocator

Previously, the boot allocator would do dynamic calculations to
minimise fragmentation, then throw away the smallest regions.
With the new boot allocator, we can reasonably predict that
fragmentation will create at most one extra region, so this commit
adds one freemem slot for ARM.

boot: refactor allocation of rootserver objects

Prior to this change, the boot process would dynamically allocate
memory for root server objects based on the order of initialisation.
Allocation was a best-fit algorithm.

This change preallocates all memory for root server objects to an
aligned untyped just after the user image. By allocating the objects in
order of size, allocation is greatly simplified and the ability to
reproduce the allocation offline based on the kernel and user image
sizes is increased.

boot: consolidate init_freemem

init_freemem sets up available regions of memory for the hardware that
seL4 is booting on. Previously this function was duplicated across
architectures, with minor duplication.

This change provides a top-level init_freemem suitable for all
architectures.

- arm/riscv: change get_avail_p_reg to return whole p_reg array
- update all architectures to use new init_freemem.
- wrap init_freemem calls with arch_init_freemem for each arch, where
arch_init_freemem sets up the available and reserved regions of memory
which are passed to init_freemem.

boot: allocate irq cnode statically

The memory used for the irq cnode is never available to the user. As a
result this memory can be allocated statically, simplifying the
bootcode.

- remove allocation of irq cnode
- add static init
- generate irq cnode size from cmake for arm
- add static constants for riscv, x86 as there is no variability at the
moment.

style: set code width to 120

style: consistently attach return type

Add attach-return-type to astyle

style: consistently align pointer with name

Run astyle with align-pointer=name

Ensure we always have enough freemem regions on ARM

Define more freemem regions on all architectures except ARM

2 freemem regions is far to prohibitive on platforms that have fragmented initial
memory. Ultimately ARM should be changed to also have more than 2, but is being
deferred for now as it will result in trivial verification breakage.

refactor: initialise common core state in one place

Remove assumption on 32-bit memory offsets

On 64-bit platforms physical address could be >2^32 offset from a virtual address. This
changes offsets to match the word size of the target architecture

Helper for allocating the extra boot info region

SELFOUR-421 Introduce explicit device frames and untypeds

Kernel objects cannot be created from device untypeds, with the
exception of frames, which do not get zeroed and cannot be used
as an IPC buffer. Device untypeds additionally cannot be used
in the construction of ASID pools.

This then changes the API to the rootserver (i.e. bootinfo) to
send device untypeds instead of device frames. On ARM these
device untypeds are the same as the previously exported device
frame regions. On x86 PCI scanning is removed and all physical
memory addresses (that are not important for kernel integrity)
are released to the user.

In order to have bits in the frame and untyped caps on ARM the
number of software ASIDs had to be reduced from 2^18 to 2^17,
and the maximum untyped size reduced from 2^31 to 2^30

SELFOUR-114: remove bootinfo.h duplication

x86: Populate the freemem list from the multiboot mem list

If the multiboot memory list exists, then it may contain more
than just the single contiguous memory region listed in 'mem_upper'
Therefore we use it to populate a more complete free memory list,
if it exists

Rename uint32_t -> word_t in any relevant places

Release snapshot