mx31: remove duplicated #include

Remove duplicated #include in arch/arm/mach-mx3/devices.c.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mx3/devices.c

@@ -22,7 +22,6 @@
 #include <linux/platform_device.h>
 #include <linux/serial.h>
 #include <linux/gpio.h>
-#include <linux/dma-mapping.h>
 #include <mach/hardware.h>
 #include <mach/irqs.h>
 #include <mach/common.h>