gpio: grgpio: Include the right header

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

drivers/gpio/gpio-grgpio.c

@@ -26,9 +26,8 @@
 #include <linux/spinlock.h>
 #include <linux/io.h>
 #include <linux/of.h>
-#include <linux/of_gpio.h>
 #include <linux/of_platform.h>
-#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/gpio/driver.h>