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_bl2u_setup.c b/plat/arm/common/arm_bl2u_setup.c
index 9f44b9e..3614c7d 100644
--- a/plat/arm/common/arm_bl2u_setup.c
+++ b/plat/arm/common/arm_bl2u_setup.c
@@ -83,10 +83,10 @@
 
 	setup_page_tables(bl_regions, plat_arm_get_mmap());
 
-#ifdef AARCH32
-	enable_mmu_svc_mon(0);
-#else
+#ifdef __aarch64__
 	enable_mmu_el1(0);
+#else
+	enable_mmu_svc_mon(0);
 #endif
 	arm_setup_romlib();
 }