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/DxeStandaloneMmAcpiTimerLib.h

@@ -0,0 +1,24 @@
+/** @file
+  Header file internal to ACPI TimerLib.
+
+Copyright (c) Microsoft Corporation.
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+
+#ifndef _DXE_STANDALONE_MM_ACPI_TIMER_LIB_H_
+#define _DXE_STANDALONE_MM_ACPI_TIMER_LIB_H_
+
+/**
+  The constructor function enables ACPI IO space, and caches PerformanceCounterFrequency.
+
+  @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.
+
+**/
+EFI_STATUS
+CommonAcpiTimerLibConstructor (
+  VOID
+  );
+
+#endif