MdeModulePkg: move arch-specific allocation granularity defines to DxeMain.h

MdeModulePkg: move arch-specific allocation granularity defines to DxeMain.h

Move the definitions of EFI_ACPI_RUNTIME_PAGE_ALLOCATION_ALIGNMENT and
DEFAULT_PAGE_ALLOCATION to DxeMain.h to make them available explicitly
to all parts of DxeCore.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: "Yao, Jiewen" <Jiewen.Yao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17811 6f19259b-4bc3-4df7-8a09-765794883524