[media] sliced vbi: subdevs shouldn't clear the full v4l2_sliced_vbi_format struct

Various subdevs cleared the full v4l2_sliced_vbi_format struct, when
only the service_set/lines fields should have been cleared.
Due to this the io_size field was wrongly cleared to 0, causing a
v4l2-compliance error.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/i2c/saa7127.c b/drivers/media/i2c/saa7127.c
index 8ecb656..b745f68 100644
--- a/drivers/media/i2c/saa7127.c
+++ b/drivers/media/i2c/saa7127.c
@@ -625,7 +625,7 @@
 {
 	struct saa7127_state *state = to_state(sd);
 
-	memset(fmt, 0, sizeof(*fmt));
+	memset(fmt->service_lines, 0, sizeof(fmt->service_lines));
 	if (state->vps_enable)
 		fmt->service_lines[0][16] = V4L2_SLICED_VPS;
 	if (state->wss_enable)