[media] uvcvideo: Set buffer field to V4L2_FIELD_NONE

The driver doesn't support interlaced video, set field to
V4L2_FIELD_NONE for all vb2 buffers.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/uvc/uvc_video.c

@@ -1021,6 +1021,7 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
 
 		uvc_video_get_ts(&ts);
 
+		buf->buf.v4l2_buf.field = V4L2_FIELD_NONE;
 		buf->buf.v4l2_buf.sequence = stream->sequence;
 		buf->buf.v4l2_buf.timestamp.tv_sec = ts.tv_sec;
 		buf->buf.v4l2_buf.timestamp.tv_usec =