ArmVirtualizationPkg: implement custom MemoryInitPeiLib

ArmVirtualizationPkg: implement custom MemoryInitPeiLib

This implements a MemoryInitPeiLib instance that differs from the
stock ArmPlatformPkg version only in the fact that it does not remove
the memory used by the flash device (FD). The reason is that, when using
PrePi, the DXE core is started immediately and never returns so there is
no reason to preserve any of the memory that the flash device occupied
originally, and it is preferable to release is so that the OS loader
can reuse it. This is especially important for the relocatable PrePi
configuration, which is aimed at being launched from a boot loader that
itself adheres to the Linux arm64 boot protocol.

Contributed-under: TianoCore Contribution Agreement 1.0
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Olivier Martin <olivier.martn@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16962 6f19259b-4bc3-4df7-8a09-765794883524