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__.)

Change-Id: Ic77de4b052297d77f38fc95f95f65a8ee70cf200
Signed-off-by: Julius Werner <jwerner@chromium.org>
diff --git a/include/common/runtime_svc.h b/include/common/runtime_svc.h
index 3b0a224..472a32a 100644
--- a/include/common/runtime_svc.h
+++ b/include/common/runtime_svc.h
@@ -20,15 +20,15 @@
  * Constants to allow the assembler access a runtime service
  * descriptor
  */
-#ifdef AARCH32
-#define RT_SVC_SIZE_LOG2	U(4)
-#define RT_SVC_DESC_INIT	U(8)
-#define RT_SVC_DESC_HANDLE	U(12)
-#else
+#ifdef __aarch64__
 #define RT_SVC_SIZE_LOG2	U(5)
 #define RT_SVC_DESC_INIT	U(16)
 #define RT_SVC_DESC_HANDLE	U(24)
-#endif /* AARCH32 */
+#else
+#define RT_SVC_SIZE_LOG2	U(4)
+#define RT_SVC_DESC_INIT	U(8)
+#define RT_SVC_DESC_HANDLE	U(12)
+#endif /* __aarch64__ */
 #define SIZEOF_RT_SVC_DESC	(U(1) << RT_SVC_SIZE_LOG2)