iio: dac: ad5380: fix incorrect assignment to val

Currently the pointer val is being incorrectly incremented
instead of the value pointed to by val. Fix this by adding
in the missing * indirection operator.

Addresses-Coverity: ("Unused value")
Fixes: c03f2c53 ("staging:iio:dac: Add AD5380 driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/ad5380.c

@@ -220,7 +220,7 @@ static int ad5380_read_raw(struct iio_dev *indio_dev,
 		if (ret)
 			return ret;
 		*val >>= chan->scan_type.shift;
-		val -= (1 << chan->scan_type.realbits) / 2;
+		*val -= (1 << chan->scan_type.realbits) / 2;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = 2 * st->vref;