mx25 devices: Add missing include

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mx25/devices.c

@@ -1,4 +1,5 @@
 #include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
 #include <linux/gpio.h>
 #include <mach/mx25.h>
 #include <mach/irqs.h>