gpio: pxa: Make of_device_id array const

Make of_device_id array const, because all OF functions handle
it as const.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-pxa.c

@@ -498,7 +498,7 @@ static int pxa_gpio_nums(struct platform_device *pdev)
 }
 
 #ifdef CONFIG_OF
-static struct of_device_id pxa_gpio_dt_ids[] = {
+static const struct of_device_id pxa_gpio_dt_ids[] = {
 	{ .compatible = "intel,pxa25x-gpio",	.data = &pxa25x_id, },
 	{ .compatible = "intel,pxa26x-gpio",	.data = &pxa26x_id, },
 	{ .compatible = "intel,pxa27x-gpio",	.data = &pxa27x_id, },