gpio: tegra: 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>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-tegra.c

@@ -408,7 +408,7 @@ static struct tegra_gpio_soc_config tegra30_gpio_config = {
 	.upper_offset = 0x80,
 };
 
-static struct of_device_id tegra_gpio_of_match[] = {
+static const struct of_device_id tegra_gpio_of_match[] = {
 	{ .compatible = "nvidia,tegra30-gpio", .data = &tegra30_gpio_config },
 	{ .compatible = "nvidia,tegra20-gpio", .data = &tegra20_gpio_config },
 	{ },