iio/adjd_s311: Fix potential memory leak in adjd_s311_update_scan_mode()

Do not leak memory by updating pointer with potentially NULL realloc return value.
There is no need to preserve data in the buffer,
so replace krealloc() by kfree()-kmalloc() pair.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: NAlexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: NPeter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/light/adjd_s311.c

@@ -271,9 +271,10 @@ static int adjd_s311_update_scan_mode(struct iio_dev *indio_dev,
 	const unsigned long *scan_mask)
 {
 	struct adjd_s311_data *data = iio_priv(indio_dev);
-	data->buffer = krealloc(data->buffer, indio_dev->scan_bytes,
-				GFP_KERNEL);
-	if (!data->buffer)
+
+	kfree(data->buffer);
+	data->buffer = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
+	if (data->buffer == NULL)
 		return -ENOMEM;
 
 	return 0;