Input: gpio_keys - add missing include to gpio_keys.h

gpio_keys.h uses 'bool' - type which is defined in linux/types.h.
Include this header.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

include/linux/gpio_keys.h

@@ -2,6 +2,8 @@
 #ifndef _GPIO_KEYS_H
 #define _GPIO_KEYS_H
 
+#include <linux/types.h>
+
 struct device;
 
 /**