ARM: samsung: Include GPIO driver header

This file is using struct gpio_chip and needs to include
<linux/gpio/driver.h> to get that.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>

arch/arm/plat-samsung/include/plat/gpio-core.h

@@ -12,6 +12,7 @@
 
 /* Bring in machine-local definitions, especially S3C_GPIO_END */
 #include <mach/gpio-samsung.h>
+#include <linux/gpio/driver.h>
 
 #define GPIOCON_OFF	(0x00)
 #define GPIODAT_OFF	(0x04)