ArmVirtualizationPkg: invalidate PEI memory region by VA

ArmVirtualizationPkg: invalidate PEI memory region by VA

This updates ArmVirtualizationMemoryInitPeiLib so that the PEI memory
region, i.e., the region that is used both before and after the MMU
and caches are enabled, is invalidated by virtual address before
enabling the MMU.

This prevents issues where data we modified with the caches and MMU
off may be shadowed by clean cachelines in system caches or in lower
level caches on other CPUs, resulting in the this data to become
invisible once we turn the MMU and caches on.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Olivier Martin <Olivier.Martin@arm.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17177 6f19259b-4bc3-4df7-8a09-765794883524