ArmPkg/ArmV7Mmu: introduce feature PCD to map normal memory non-shareable

ArmPkg/ArmV7Mmu: introduce feature PCD to map normal memory non-shareable

Even though mapping normal memory (inner) shareable is usually the
correct choice on coherent systems, it may be desirable in some cases
to use non-shareable mappings for normal memory, e.g., when hardware
managed coherency is not required and the memory system is not fully
configured yet. So introduce a PCD PcdNormalMemoryNonshareableOverride
that makes cacheable mappings of normal memory non-shareable.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18897 6f19259b-4bc3-4df7-8a09-765794883524