regulator: st-pwm: 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: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/regulator/st-pwm.c

@@ -118,7 +118,7 @@ static const struct st_pwm_regulator_pdata b2105_info = {
 	.duty_cycle_table = b2105_duty_cycle_table,
 };
 
-static struct of_device_id st_pwm_of_match[] = {
+static const struct of_device_id st_pwm_of_match[] = {
 	{ .compatible = "st,b2105-pwm-regulator", .data = &b2105_info, },
 	{ },
 };