ArmVirtPkg/ArmVirtQemu: implement ArmPlatformLib with static ID map

ArmVirtPkg/ArmVirtQemu: implement ArmPlatformLib with static ID map

To substantially reduce the amount of processing that takes place with
the MMU and caches off, implement a version of ArmPlatformLib specific
for QEMU/mach-virt in AArch64 mode that carries a statically allocated
and populated ID map that covers the NOR flash and device region, and
128 MiB of DRAM at the base of memory (0x4000_0000).

Note that 128 MiB has always been the minimum amount of DRAM we support
for this configuration, and the existing code already ASSERT()s in DEBUG
mode when booting with less.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>