arm64, acpi/apei: Implement arch_apei_get_mem_attributes()

arm64, acpi/apei: Implement arch_apei_get_mem_attributes()

Table 8 of UEFI 2.5 section 2.3.6.1 defines mappings from EFI
memory types to MAIR attribute encodings for arm64.

If the physical address has memory attributes defined by EFI
memmap as EFI_MEMORY_[UC|WC|WT], return approprate page
protection type according to the UEFI spec. Otherwise, return
PAGE_KERNEL.

Signed-off-by: Jonathan (Zhixiong) Zhang <[email protected]>
Signed-off-by: Matt Fleming <[email protected]>
[ Small stylistic tweaks. ]
Reviewed-by: Matt Fleming <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Acked-by: Hanjun Guo <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>