StandaloneMmPkg: build for 32bit arm machines

This change allows to build StandaloneMmPkg components for 32bit Arm
StandaloneMm firmware.

This change mainly moves AArch64/ source files to Arm/ side directory
for several components:  StandaloneMmCpu, StandaloneMmCoreEntryPoint
and StandaloneMmMemLib. The source file is built for both 32b and 64b
Arm targets.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

StandaloneMmPkg/Drivers/StandaloneMmCpu/EventHandle.c

@@ -2,6 +2,7 @@
 
   Copyright (c) 2016 HP Development Company, L.P.
   Copyright (c) 2016 - 2021, Arm Limited. All rights reserved.
+  Copyright (c) 2021, Linaro Limited
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -92,8 +93,8 @@ PiMmStandaloneArmTfCpuDriverEntry (
   // receipt of a synchronous MM request. Use the Event ID to distinguish
   // between synchronous and asynchronous events.
   //
-  if ((ARM_SMC_ID_MM_COMMUNICATE_AARCH64 != EventId) &&
-      (ARM_SVC_ID_FFA_MSG_SEND_DIRECT_REQ_AARCH64 != EventId)) {
+  if ((ARM_SMC_ID_MM_COMMUNICATE != EventId) &&
+      (ARM_SVC_ID_FFA_MSG_SEND_DIRECT_REQ != EventId)) {
     DEBUG ((DEBUG_INFO, "UnRecognized Event - 0x%x\n", EventId));
     return EFI_INVALID_PARAMETER;
   }

StandaloneMmPkg/Drivers/StandaloneMmCpu/StandaloneMmCpu.c

@@ -10,7 +10,7 @@
 
 #include <Base.h>
 #include <Pi/PiMmCis.h>
-#include <Library/AArch64/StandaloneMmCoreEntryPoint.h>
+#include <Library/Arm/StandaloneMmCoreEntryPoint.h>
 #include <Library/DebugLib.h>
 #include <Library/ArmSvcLib.h>
 #include <Library/ArmLib.h>