Input: gpio_keys_polled - include linux/of.h header

'of_match_ptr' is defined in linux/of.h. Include it explicitly.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/gpio_keys_polled.c

@@ -25,6 +25,7 @@
 #include <linux/platform_device.h>
 #include <linux/gpio.h>
 #include <linux/gpio_keys.h>
+#include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/of_gpio.h>