ArmVirtualizationPkg: make ArmVirtualizationMemoryInitPeiLib the default

ArmVirtualizationPkg: make ArmVirtualizationMemoryInitPeiLib the default

This updates ArmVirtualization.dsc.inc to use the MemoryInitPeiLib
implementation for virt targets. The only difference between that one
and the original one is that the original one removes memory from the
available list if it overlaps the FD region (which may be the case when
shadowing NOR flash with system RAM). This is never the case for the
Qemu target, which is the only platform affected by this change, since
the Xen target already uses this library explicitly.

This allows us to remove the Xen-specific declaration of this library
dependency. For the Qemu target, this change will not take effect until
after the MemoryInitPeim<->MemoryInitPeiLib dependency resolution is
fixed in a subsequent patch.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Olivier Martin <olivier.martin@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17174 6f19259b-4bc3-4df7-8a09-765794883524