Staging: iio/light/tsl2563: unlock on an error path

We need to unlock here before returning.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/light/tsl2563.c

@@ -518,7 +518,8 @@ static int tsl2563_read_raw(struct iio_dev *indio_dev,
 		ret = IIO_VAL_INT;
 		break;
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
+		goto error_ret;
 	}
 
 error_ret: