backlight: lm3639: Remove unnecessary return statements

Fixed the following checkpatch warning.

  WARNING: void function return statements are not generally useful
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/video/backlight/lm3639_bl.c

@@ -254,7 +254,6 @@ static void lm3639_torch_brightness_set(struct led_classdev *cdev,
 	return;
 out:
 	dev_err(pchip->dev, "i2c failed to access register\n");
-	return;
 }
 
 /* flash */
@@ -293,7 +292,6 @@ static void lm3639_flash_brightness_set(struct led_classdev *cdev,
 	return;
 out:
 	dev_err(pchip->dev, "i2c failed to access register\n");
-	return;
 }
 
 static const struct regmap_config lm3639_regmap = {