x86, acpi: Introduce x86 arch specific arch_reserve_mem_area() for e820 handling

x86, acpi: Introduce x86 arch specific arch_reserve_mem_area() for e820 handling

This is needed for ACPI table overriding via initrd. Beside reserving
memblocks, X86 also requires to flag the memory area to E820_RESERVED or
E820_ACPI in the e820 mappings to be able to io(re)map it later.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Link: http://lkml.kernel.org/r/1349043837-22659-3-git-send-email-trenn@suse.de
Cc: Len Brown <lenb@kernel.org>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>