hwmon: (gpio-fan) 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: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/gpio-fan.c

@@ -482,7 +482,7 @@ static int gpio_fan_get_of_pdata(struct device *dev,
 	return 0;
 }
 
-static struct of_device_id of_gpio_fan_match[] = {
+static const struct of_device_id of_gpio_fan_match[] = {
 	{ .compatible = "gpio-fan", },
 	{},
 };