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/lib/utils_def.h b/include/lib/utils_def.h
index 7098bac..35ae33a 100644
--- a/include/lib/utils_def.h
+++ b/include/lib/utils_def.h
@@ -21,10 +21,10 @@
 #define BIT_32(nr)			(U(1) << (nr))
 #define BIT_64(nr)			(ULL(1) << (nr))
 
-#ifdef AARCH32
-#define BIT				BIT_32
-#else
+#ifdef __aarch64__
 #define BIT				BIT_64
+#else
+#define BIT				BIT_32
 #endif
 
 /*
@@ -46,10 +46,10 @@
 	(((~UINT64_C(0)) << (l)) & (~UINT64_C(0) >> (64 - 1 - (h))))
 #endif
 
-#ifdef AARCH32
-#define GENMASK				GENMASK_32
-#else
+#ifdef __aarch64__
 #define GENMASK				GENMASK_64
+#else
+#define GENMASK				GENMASK_32
 #endif
 
 /*
@@ -109,10 +109,10 @@
 	((_u32) > (UINT32_MAX - (_inc)))
 
 /* Register size of the current architecture. */
-#ifdef AARCH32
-#define REGSZ		U(4)
-#else
+#ifdef __aarch64__
 #define REGSZ		U(8)
+#else
+#define REGSZ		U(4)
 #endif
 
 /*