gpio: lpc32xx: Make of_device_id array const

Make of_device_id array const, because all OF functions handle
it as const.
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Acked-By: NRoland Stigge <stigge@antcom.de>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-lpc32xx.c

@@ -560,7 +560,7 @@ static int lpc32xx_gpio_probe(struct platform_device *pdev)
 }
 
 #ifdef CONFIG_OF
-static struct of_device_id lpc32xx_gpio_of_match[] = {
+static const struct of_device_id lpc32xx_gpio_of_match[] = {
 	{ .compatible = "nxp,lpc3220-gpio", },
 	{ },
 };