iio: adc: ad799x: change 'unsigned' to 'unsigned int' declaration

Prefer 'unsigned int' instead of bare use of 'unsigned' declarations to
to improve code readbility. This ceases one of the warning messages
pointed by checkpatch.

Co-developed-by: Bruna Lopes <brunaafl@usp.br>
Signed-off-by: Bruna Lopes <brunaafl@usp.br>
Signed-off-by: Gustavo Rodrigues <ogustavo@usp.br>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240428194326.2836387-2-ogustavo@usp.br
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: Gustavo Rodrigues

drivers/iio/adc/ad799x.c

@@ -128,7 +128,7 @@ struct ad799x_state {
 	struct regulator		*vref;
 	/* lock to protect against multiple access to the device */
 	struct mutex			lock;
-	unsigned			id;
+	unsigned int			id;
 	u16				config;
 
 	u8				*rx_buf;
@@ -253,7 +253,7 @@ static int ad799x_update_scan_mode(struct iio_dev *indio_dev,
 	}
 }
 
-static int ad799x_scan_direct(struct ad799x_state *st, unsigned ch)
+static int ad799x_scan_direct(struct ad799x_state *st, unsigned int ch)
 {
 	u8 cmd;