UefiCpuPkg: Add a new CPU IO 2 driver named CpuMmio2Dxe

CpuIo2Dxe only supports IO to access to CPU IO. Some ARCHs that do not
implement ports for CPU IO require MMIO to access PCI IO, and they
pretty much put the IO devices under the LPC bus, which is usually under
the PCIe/PCI bus. CpuMmio2Dxe was added to meet these needs.

CpuMmio2Dxe depends on PcdPciIoTranslation. The code is copied from
ArmPkg.

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4584

Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Chao Li <lichao@loongson.cn>
Reviewed-by: Ray Ni <ray.ni@intel.com>

UefiCpuPkg/UefiCpuPkg.dsc

@@ -206,6 +206,7 @@
   UefiCpuPkg/Library/BaseRiscVMmuLib/BaseRiscVMmuLib.inf
   UefiCpuPkg/CpuTimerDxeRiscV64/CpuTimerDxeRiscV64.inf
   UefiCpuPkg/CpuDxeRiscV64/CpuDxeRiscV64.inf
+  UefiCpuPkg/CpuMmio2Dxe/CpuMmio2Dxe.inf
 
 [BuildOptions]
   *_*_*_CC_FLAGS = -D DISABLE_NEW_DEPRECATED_INTERFACES