mfd: tps6586x: 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>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/tps6586x.c

@@ -444,7 +444,7 @@ static struct tps6586x_platform_data *tps6586x_parse_dt(struct i2c_client *clien
 	return pdata;
 }
 
-static struct of_device_id tps6586x_of_match[] = {
+static const struct of_device_id tps6586x_of_match[] = {
 	{ .compatible = "ti,tps6586x", },
 	{ },
 };