pc99: Explicitly declare sizes for different versions of ACPI RSDP

pc99: Provide public function for validating an RSDP

RSDP validation was previously done directly in acpi_init. This splits the validation
into a seperate, publicly useable, function. The intention is for this to be used in
boot scenarios where an RSDP is given and does not need to be searched for.

x86: Copy RSDP table in acpi_init instead of returning physical address of rsdt

The full RSDP is useful beyond just extracting the RSDT address out of it. In particular
this prepares us for being able to pass a copy of the RSDP to the rootserver.

The previous function signature might lead a user to believe that they were getting a
pointer to a useable acpi_rsdt_t structure. This was in fact not the case and was
actually returning the physical address, that may or may not be mapped in, of the rsdt
table. All of the other acpi *_scan functions would therefore immediately map in the physical
rsdt pointer they were given.

This commit changes acpi_init to return a boolean indicating whether it found a valid
rsdp, and then fills in a copy of the rsdp data. The copy is necessary as the rsdp
data may be at a temporary mapping.

As a result of changing acpi_init the boot code and state is changed to have a acpi_rsdt_t
instance that can be filled out.

x86: add logical id mapping for x2APIC IPI boradcasting

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

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: Port some of the IOMMU changes on the experimental branch

This changes the IOMMU from using passthrough devices and instead
directly mapping in the reserved regions that are needed for each
device.

x86: Do not conditionally compile IOMMU code, use build/run time checks

Guarding code with #ifdef's makes even cursor testing of 'does this code compile'
difficult due to code being hidden by the pre-processor. Using config_set in
regular C if statements is performant as the compiler can trivially detect
dead code at compile time, and at -O1 and above will not even link in symbols
referenced by dead code in these blocks, so this will not bloat image size

ia32: Explicitly pack ACPI structs

Use explicit struct packing instead of using compiler asserts
to check that packing happened as expected

ia32: Use explicitly sized types for ACPI tables

The ACPI standard says these fields are 32bits, not the size
of a machine word or pointer

Support IOAPIC on ia32 and modify interrupt handling to support user level setting of modes

Release snapshot