iio:temp:mlx90614 trivial drop of unnecessary ret return from write_raw.

This is mostly part of an effort to clean out our current warnings
and make the autobuilder build reports more useful.

Still a worthwhile if trivial cleanup!
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Vianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>
Cc: Peter Meerwald <pmeerw@pmeerw.net>

drivers/iio/temperature/mlx90614.c

@@ -254,9 +254,7 @@ static int mlx90614_write_raw(struct iio_dev *indio_dev,
 		mutex_unlock(&data->lock);
 		mlx90614_power_put(data);
 
-		if (ret < 0)
-			return ret;
-		return 0;
+		return ret;
 	default:
 		return -EINVAL;
 	}