PcAtChipsetPkg: AcpiTimerLib: Added StandaloneMm instance of AcpiTimerLib

This change added a new instance of AcpiTimerLib for StandaloneMm core
and drivers. It centralizes the common routines into shared files and
abstract the library constructor into corresponding files to accommodate
each constructor function prototypes.

Cc: Ray Ni <ray.ni@intel.com>

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

PcAtChipsetPkg/Library/AcpiTimerLib/StandaloneMmAcpiTimerLib.c

@@ -0,0 +1,31 @@
+/** @file
+  ACPI Timer implements one instance of Timer Library.
+
+  Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) Microsoft Corporation.
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <PiMm.h>
+
+#include "DxeStandaloneMmAcpiTimerLib.h"
+
+/**
+  The constructor function enables ACPI IO space, and caches PerformanceCounterFrequency.
+
+  @param  ImageHandle   The firmware allocated handle for the EFI image.
+  @param  SystemTable   A pointer to the EFI System Table.
+
+  @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.
+
+**/
+EFI_STATUS
+EFIAPI
+StandaloneMmAcpiTimerLibConstructor (
+  IN EFI_HANDLE           ImageHandle,
+  IN EFI_MM_SYSTEM_TABLE  *SystemTable
+  )
+{
+  return CommonAcpiTimerLibConstructor ();
+}