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/lib/xlat_tables_v2/xlat_tables_utils.c b/lib/xlat_tables_v2/xlat_tables_utils.c
index 761d00c..232142e 100644
--- a/lib/xlat_tables_v2/xlat_tables_utils.c
+++ b/lib/xlat_tables_v2/xlat_tables_utils.c
@@ -97,7 +97,7 @@
 
 	printf(((LOWER_ATTRS(NS) & desc) != 0ULL) ? "-NS" : "-S");
 
-#ifdef AARCH64
+#ifdef __aarch64__
 	/* Check Guarded Page bit */
 	if ((desc & GP) != 0ULL) {
 		printf("-GP");