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/plat/arm/common/arm_common.c b/plat/arm/common/arm_common.c
index f5ce4d2..bc0cf9a 100644
--- a/plat/arm/common/arm_common.c
+++ b/plat/arm/common/arm_common.c
@@ -59,7 +59,7 @@
 /*******************************************************************************
  * Gets SPSR for BL33 entry
  ******************************************************************************/
-#ifndef AARCH32
+#ifdef __aarch64__
 uint32_t arm_get_spsr_for_bl33_entry(void)
 {
 	unsigned int mode;
@@ -97,7 +97,7 @@
 			SPSR_E_LITTLE, DISABLE_ALL_EXCEPTIONS);
 	return spsr;
 }
-#endif /* AARCH32 */
+#endif /* __aarch64__ */
 
 /*******************************************************************************
  * Configures access to the system counter timer module.