iio: amplifiers: ad8366: Use right order for type specification

This patch fixes the following checkpatch.pl warning:
WARNING: type 'char unsigned' should be specified in [[un]signed]
[short|int|long|long long] order
Signed-off-by: Roberta Dobrescu <roberta.dobrescu@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/amplifiers/ad8366.c

@@ -31,7 +31,7 @@ struct ad8366_state {
 };
 
 static int ad8366_write(struct iio_dev *indio_dev,
-			unsigned char ch_a, char unsigned ch_b)
+			unsigned char ch_a, unsigned char ch_b)
 {
 	struct ad8366_state *st = iio_priv(indio_dev);
 	int ret;