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_nor_psci_mem_protect.c b/plat/arm/common/arm_nor_psci_mem_protect.c
index 3a70059..b9181eb 100644
--- a/plat/arm/common/arm_nor_psci_mem_protect.c
+++ b/plat/arm/common/arm_nor_psci_mem_protect.c
@@ -26,7 +26,7 @@
 
 static mem_region_t arm_ram_ranges[] = {
 	{DRAM1_NS_IMAGE_LIMIT, DRAM1_PROTECTED_SIZE},
-#ifdef AARCH64
+#ifdef __aarch64__
 	{ARM_DRAM2_BASE, 1u << ONE_GB_SHIFT},
 #endif
 };