ARM i.MX: remove duplicated #include

Remove duplicated #include('s) in
  arch/arm/mach-mx5/mx51_efika.c

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mx5/mx51_efika.c

@@ -42,7 +42,6 @@
 #include <asm/mach-types.h>
 #include <asm/mach/arch.h>
 #include <asm/mach/time.h>
-#include <asm/mach-types.h>
 
 #include "devices-imx51.h"
 #include "devices.h"