ArmPkg/ArmLib: avoid cache maintenance in PEIMs when executing in place

ArmPkg/ArmLib: avoid cache maintenance in PEIMs when executing in place

On some platforms, performing cache maintenance on regions that are backed
by NOR flash result in SErrors. Since cache maintenance is unnecessary in
that case, create a PEIM specific version that only performs said cache
maintenance in its constructor if the module is shadowed in RAM. To avoid
performing the cache maintenance if the MMU code is not used to begin with,
check that explicitly in the constructor.

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