iio: mlx90614: Fix duplicate const warning

Fix a typo triggering a duplicate const warning on some compilers.
Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/temperature/mlx90614.c

@@ -263,7 +263,7 @@ static int mlx90614_write_raw(struct iio_dev *indio_dev,
 }
 
 static int mlx90614_write_raw_get_fmt(struct iio_dev *indio_dev,
-				     const struct iio_chan_spec const *channel,
+				     struct iio_chan_spec const *channel,
 				     long mask)
 {
 	switch (mask) {