iio: adc: ad799x: remove space before comma

This fixes the error reported by checkpatch.pl:

ERROR: space prohibited before that ',' (ctx:WxW)
Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/ad799x.c

@@ -477,7 +477,7 @@ static int ad799x_read_event_value(struct iio_dev *indio_dev,
 	if (ret < 0)
 		return ret;
 	*val = (ret >> chan->scan_type.shift) &
-		GENMASK(chan->scan_type.realbits - 1 , 0);
+		GENMASK(chan->scan_type.realbits - 1, 0);
 
 	return IIO_VAL_INT;
 }