iio: st_sensors: Fix buffer copy

Use byte_for_channel as iterator to properly initialize the buffer.

Signed-off-by: Robin van der Gracht <robin@protonic.nl>
Acked-by: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: <Stable@vger.kernel.org>
diff --git a/drivers/iio/common/st_sensors/st_sensors_buffer.c b/drivers/iio/common/st_sensors/st_sensors_buffer.c
index 1665c8e..e18bc67 100644
--- a/drivers/iio/common/st_sensors/st_sensors_buffer.c
+++ b/drivers/iio/common/st_sensors/st_sensors_buffer.c
@@ -71,7 +71,7 @@
 				goto st_sensors_free_memory;
 			}
 
-			for (i = 0; i < n * num_data_channels; i++) {
+			for (i = 0; i < n * byte_for_channel; i++) {
 				if (i < n)
 					buf[i] = rx_array[i];
 				else