SecurityPkg: add null version of RpmcLib

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2594

Add null version of RpmcLib instance. The full version should be provided
by platform which supports RPMC device.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Nishant C Mistry <nishant.c.mistry@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

SecurityPkg/Library/RpmcLibNull/RpmcLibNull.c

@@ -0,0 +1,47 @@
+/** @file
+  NULL RpmcLib instance for build purpose.
+
+Copyright (c) 2020, Intel Corporation. All rights reserved.<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Library/DebugLib.h>
+#include <Library/RpmcLib.h>
+
+/**
+  Requests the monotonic counter from the designated RPMC counter.
+
+  @param[out]   CounterValue            A pointer to a buffer to store the RPMC value.
+
+  @retval       EFI_SUCCESS             The operation completed successfully.
+  @retval       EFI_DEVICE_ERROR        A device error occurred while attempting to update the counter.
+  @retval       EFI_UNSUPPORTED         The operation is un-supported.
+**/
+EFI_STATUS
+EFIAPI
+RequestMonotonicCounter (
+  OUT UINT32  *CounterValue
+  )
+{
+  ASSERT (FALSE);
+  return EFI_UNSUPPORTED;
+}
+
+/**
+  Increments the monotonic counter in the SPI flash device by 1.
+
+  @retval       EFI_SUCCESS             The operation completed successfully.
+  @retval       EFI_DEVICE_ERROR        A device error occurred while attempting to update the counter.
+  @retval       EFI_UNSUPPORTED         The operation is un-supported.
+**/
+EFI_STATUS
+EFIAPI
+IncrementMonotonicCounter (
+  VOID
+  )
+{
+  ASSERT (FALSE);
+  return EFI_UNSUPPORTED;
+}
+