ArmPlatformPkg/MemoryInitPeim: handle memory above 4 GB on 32-bit ARM

ArmPlatformPkg/MemoryInitPeim: handle memory above 4 GB on 32-bit ARM

Make sure that the PEI memory region is carved out of memory that is
32-bit addressable, by taking MAX_ADDRESS into account (which is
defined as '4 GB - 1' on ARM)

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18426 6f19259b-4bc3-4df7-8a09-765794883524