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/el3_runtime/pubsub_events.h b/include/lib/el3_runtime/pubsub_events.h
index 8e4a87a..5012082 100644
--- a/include/lib/el3_runtime/pubsub_events.h
+++ b/include/lib/el3_runtime/pubsub_events.h
@@ -24,7 +24,7 @@
 REGISTER_PUBSUB_EVENT(psci_suspend_pwrdown_start);
 REGISTER_PUBSUB_EVENT(psci_suspend_pwrdown_finish);
 
-#ifdef AARCH64
+#ifdef __aarch64__
 /*
  * These events are published by the AArch64 context management framework
  * after the secure context is restored/saved via
@@ -40,4 +40,4 @@
  */
 REGISTER_PUBSUB_EVENT(cm_entering_normal_world);
 REGISTER_PUBSUB_EVENT(cm_exited_normal_world);
-#endif /* AARCH64 */
+#endif /* __aarch64__ */