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.

x86: move boot_state definition to boot_sys.h

This is because future work needs to access the rmrr_list globally.

style: consistently align pointer with name

Run astyle with align-pointer=name

x86: Support for mulitboot2 compatible booting

Declares to a bootloader that we hare multiboot2 compliant and provides an additional
try_boot_sys_mbi2 function for processing a multiboot2 information header.

x86: Remove assumptions on multiboot1 style booting

This abstracts the existing try_boot_sys into two portions, one which pulls data out
of a multiboot1 style information header, and one which performs generic booting
without being multiboot1 specific.

x86: Remove unused function

SELFOUR-630:preliminary booting application processors
- update core detection code and Kconfig file
- update kernel stack managment so that BSP does not use boot stack before IPI APs
- move arch dependant data to a single structure
- add cache line size to Kconfig
- add cpu indexing and apic id mapping
- boot APs to halting state
- add guard for kernel stack if there is only one core

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

Revert "Merge pull request #358 in SEL4/sel4 from ~AZARRABI/sel4:multicore to master"

This reverts commit ce2f666bb811c5e4c779829fcb09d5a189ebcdbb, reversing
changes made to dc183f96b81f2344d7d0d910fc430f924eaae940.

SELFOUR-630:preliminary booting application processors
- update core detection code and Kconfig file
- update kernel stack managment so that BSP does not use boot stack before IPI APs
- move arch dependant data to a single structure
- add cache line size to Kconfig
- add cpu indexing and apic id mapping
- boot APs to halting state
- add guard for kernel stack if there is only one core

x86: Strip multi kernel support from the x86 kernel. This is not used and is conflicting with planned future features

x86: Move APIC frequency calculation to APIC init, instead of doing it before we initialize paging

x86: Make x86 the name of the architecture instead of IA32

IA32 is 32bit version of the x86 architecture. Whilst only IA32
is supported, much of the code is generic x86. Using a generic
x86 architecture will aid in future 64bit support