staging: iio: tsl2583: change tsl2583_als_calibrate() to return 0 on success

tsl2583_als_calibrate() returns the newly computed gain_trim if the
calibration was successful. This function is only called by
in_illuminance_calibrate_store() and the return value inside that
sysfs attribute is only checked to see if an error was returned.
This patch changes tsl2583_als_calibrate() to return 0 on success.
Signed-off-by: NBrian Masney <masneyb@onstation.org>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/staging/iio/light/tsl2583.c

@@ -348,7 +348,7 @@ static int tsl2583_als_calibrate(struct iio_dev *indio_dev)
 
 	chip->als_settings.als_gain_trim = (int)gain_trim_val;
 
-	return (int)gain_trim_val;
+	return 0;
 }
 
 static int tsl2583_set_als_time(struct tsl2583_chip *chip)