gpio: ml_ioh: Include the right header

This is a driver so include only <linux/gpio/driver.h>.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-ml-ioh.c

@@ -18,7 +18,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/pci.h>
-#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>