[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/cx25840/cx25840-vbi.c b/drivers/media/i2c/cx25840/cx25840-vbi.c
index 64a4004..c39e91d 100644
--- a/drivers/media/i2c/cx25840/cx25840-vbi.c
+++ b/drivers/media/i2c/cx25840/cx25840-vbi.c
@@ -96,7 +96,8 @@
 	int is_pal = !(state->std & V4L2_STD_525_60);
 	int i;
 
-	memset(svbi, 0, sizeof(*svbi));
+	memset(svbi->service_lines, 0, sizeof(svbi->service_lines));
+	svbi->service_set = 0;
 	/* we're done if raw VBI is active */
 	if ((cx25840_read(client, 0x404) & 0x10) == 0)
 		return 0;