MdePkg/ProcessorBind: add defines for page allocation granularity

The UEFI spec differs between architectures in the minimum alignment
and granularity of page allocations that are visible to the OS as
EFI_MEMORY_RUNTIME regions.

So define macros that carry these values to the respective ProcessorBind.h
header files.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>