Move spinlock library code to AArch64 folder

This patch moves the assembly exclusive lock library code
`spinlock.S` into architecture specific folder `aarch64`.
A stub file which includes the file from new location is
retained at the original location for compatibility. The BL
makefiles are also modified to include the file from the new
location.

Change-Id: Ide0b601b79c439e390c3a017d93220a66be73543
diff --git a/lib/locks/exclusive/spinlock.S b/lib/locks/exclusive/spinlock.S
index 772f14e..9c945f9 100644
--- a/lib/locks/exclusive/spinlock.S
+++ b/lib/locks/exclusive/spinlock.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -28,25 +28,6 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <asm_macros.S>
-
-	.globl	spin_lock
-	.globl	spin_unlock
-
-
-func spin_lock
-	mov	w2, #1
-	sevl
-l1:	wfe
-l2:	ldaxr	w1, [x0]
-	cbnz	w1, l1
-	stxr	w1, w2, [x0]
-	cbnz	w1, l2
-	ret
-endfunc spin_lock
-
-
-func spin_unlock
-	stlr	wzr, [x0]
-	ret
-endfunc spin_unlock
+#if !ERROR_DEPRECATED
+#include "./aarch64/spinlock.S"
+#endif