Switch AARCH32/AARCH64 to __aarch64__

NOTE: AARCH32/AARCH64 macros are now deprecated in favor of __aarch64__.

All common C compilers pre-define the same macros to signal which
architecture the code is being compiled for: __arm__ for AArch32 (or
earlier versions) and __aarch64__ for AArch64. There's no need for TF-A
to define its own custom macros for this. In order to unify code with
the export headers (which use __aarch64__ to avoid another dependency),
let's deprecate the AARCH32 and AARCH64 macros and switch the code base
over to the pre-defined standard macro. (Since it is somewhat
unintuitive that __arm__ only means AArch32, let's standardize on only
using __aarch64__.)

NOTE: This change is based on below TFA commit
https://github.com/ARM-software/arm-trusted-firmware/commit/402b3cf8766fe2cb4ae462f7ee7761d08a1ba56c

Signed-off-by: Deepika Bhavnani <deepika.bhavnani@arm.com>
Change-Id: If2c3dbaeb01d4a9d8cfd95d906e5eaf4ae94417f
diff --git a/tftf/tests/runtime_services/generic/generic_smc.c b/tftf/tests/runtime_services/generic/generic_smc.c
index dc0b102..6d057a6 100644
--- a/tftf/tests/runtime_services/generic/generic_smc.c
+++ b/tftf/tests/runtime_services/generic/generic_smc.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, Arm Limited. All rights reserved.
+ * Copyright (c) 2018-2020, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -236,7 +236,7 @@
 	return TEST_RESULT_SUCCESS;
 }
 
-#ifdef AARCH32
+#ifndef __aarch64__
 static test_result_t smc64_fast_caller32(void)
 {
 	/* Valid Fast SMC32 using all 4 return values. */
@@ -295,12 +295,12 @@
 
 	return TEST_RESULT_SUCCESS;
 }
-#endif /* AARCH32 */
+#endif /* !__aarch64__ */
 
 /* Exercise SMC64 calling convention with fast SMC calls. */
 test_result_t smc64_fast(void)
 {
-#ifdef AARCH32
+#ifndef __aarch64__
 	return smc64_fast_caller32();
 #else
 	return smc64_fast_caller64();