backlight: pwm_bl: Handle gpio that can sleep

Some backlight GPIOs might be connected to some i2c based expanders whose
access might sleep.

Since it's not in any critical path, use the cansleep variant of the GPIO
API.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/video/backlight/pwm_bl.c

@@ -55,7 +55,7 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
 		dev_err(pb->dev, "failed to enable power supply\n");
 
 	if (pb->enable_gpio)
-		gpiod_set_value(pb->enable_gpio, 1);
+		gpiod_set_value_cansleep(pb->enable_gpio, 1);
 
 	pwm_enable(pb->pwm);
 	pb->enabled = true;
@@ -70,7 +70,7 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
 	pwm_disable(pb->pwm);
 
 	if (pb->enable_gpio)
-		gpiod_set_value(pb->enable_gpio, 0);
+		gpiod_set_value_cansleep(pb->enable_gpio, 0);
 
 	regulator_disable(pb->power_supply);
 	pb->enabled = false;