imx5: Add include guards for include/asm/arch-mx5/sys_proto.h file

Signed-off-by: Lukasz Majewski <lukma@denx.de>

arch/arm/include/asm/arch-mx5/sys_proto.h

@@ -4,5 +4,9 @@
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */
+#ifndef __SYS_PROTO_IMX5_
+#define __SYS_PROTO_IMX5_
 
 #include <asm/mach-imx/sys_proto.h>
+
+#endif /* __SYS_PROTO_IMX5_ */