Replace __ASSEMBLY__ with compiler-builtin __ASSEMBLER__

NOTE: __ASSEMBLY__ macro is now deprecated in favor of __ASSEMBLER__.

All common C compilers predefine a macro called __ASSEMBLER__ when
preprocessing a .S file. There is no reason for TF-A to define it's own
__ASSEMBLY__ macro for this purpose instead. To unify code with the
export headers (which use __ASSEMBLER__ to avoid one extra dependency),
let's deprecate __ASSEMBLY__ and switch the code base over to the
predefined standard.

Change-Id: Id7d0ec8cf330195da80499c68562b65cb5ab7417
Signed-off-by: Julius Werner <jwerner@chromium.org>
diff --git a/include/common/debug.h b/include/common/debug.h
index f8faf68..245e698 100644
--- a/include/common/debug.h
+++ b/include/common/debug.h
@@ -27,7 +27,7 @@
 #define LOG_LEVEL_INFO			U(40)
 #define LOG_LEVEL_VERBOSE		U(50)
 
-#ifndef __ASSEMBLY__
+#ifndef __ASSEMBLER__
 
 #include <cdefs.h>
 #include <stdarg.h>
@@ -110,5 +110,5 @@
 void tf_log(const char *fmt, ...) __printflike(1, 2);
 void tf_log_set_max_level(unsigned int log_level);
 
-#endif /* __ASSEMBLY__ */
+#endif /* __ASSEMBLER__ */
 #endif /* DEBUG_H */