UefiCpuPkg: CpuIo2Smm: Support of CpuIo driver under StandaloneMm

This change adds a new CpuIo driver instance for MM_STANDALONE type. The
new driver entrypoint is implemented in a separate file to match the
interface definition of MM_STANDALONE modules.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>

Signed-off-by: Kun Qin <kun.q@outlook.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>

UefiCpuPkg/CpuIo2Smm/CpuIo2StandaloneMm.c

@@ -0,0 +1,32 @@
+/** @file
+  Produces the SMM CPU I/O Protocol.
+
+Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) Microsoft Corporation.
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <PiMm.h>
+
+#include "CpuIo2Mm.h"
+
+/**
+  The module Entry Point for Standalone MM CpuIoProtocol driver
+
+  @param[in] ImageHandle  The firmware allocated handle for the EFI image.
+  @param[in] SystemTable  A pointer to the EFI System Table.
+
+  @retval EFI_SUCCESS  The entry point is executed successfully.
+  @retval Other        Some error occurs when executing this entry point.
+
+**/
+EFI_STATUS
+EFIAPI
+StandaloneMmCpuIo2Initialize (
+  IN EFI_HANDLE           ImageHandle,
+  IN EFI_MM_SYSTEM_TABLE  *SystemTable
+  )
+{
+  return CommonCpuIo2Initialize ();
+}