iio: dac: ad7303: remove an unneeded check

"ret" is zero here. There is no need to check again.

Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/dac/ad7303.c

···
 	ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);
 
 	mutex_unlock(&indio_dev->mlock);
-	return ret ? ret : len;
+	return len;
 }
 
 static int ad7303_get_vref(struct ad7303_state *st,