drivers/gpio/gpio-grgpio.c: Remove duplicate header

Remove linux/gpio/driver.h which is included more than once
Signed-off-by: Brajeswar Ghosh <brajeswar.linux@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-grgpio.c

@@ -30,7 +30,6 @@
 #include <linux/gpio/driver.h>
 #include <linux/slab.h>
 #include <linux/err.h>
-#include <linux/gpio/driver.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>