ArmPkg/ArmMmuLib: add PEI specific version of ArmMmuLib

ArmPkg/ArmMmuLib: add PEI specific version of ArmMmuLib

This introduces a special version of ArmMmuLib for PEIMs that takes care
only to perform cache maintenance on the live entry replacement routine
if the module is not executing in place. Not only is such cache maintenance
unnecessary in that case, it may be actively harmful on some systems that
fail to tolerate cache maintenance operations on NOR flash regions.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>