ArmVirtualizationPkg/PciHostBridgeDxe: IO space is emulated with MMIO

ArmVirtualizationPkg/PciHostBridgeDxe: IO space is emulated with MMIO

There is no IO space on ARM, and there are no special instructions that
access it. QEMU emulates the IO space for PCI devices with a special MMIO
range. We're ready to use it at this point, we just have to switch the
Io(Read|Write)(8|16|32) primitives to their MMIO counterparts, because in
"MdePkg/Library/BaseIoLibIntrinsic/IoLibArm.c", the IO primitives
correctly ASSERT (FALSE).

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Olivier Martin <Olivier.martin@arm.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16900 6f19259b-4bc3-4df7-8a09-765794883524