[MIPS] Fix typo in header guard

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

include/asm-mips/rtlx.h

@@ -3,7 +3,7 @@
  *
  */
 
-#ifndef __ASM_RTLX_H
+#ifndef __ASM_RTLX_H_
 #define __ASM_RTLX_H_
 
 #include <irq.h>