v4l2object: Need keep same transfer as input caps.
GST_VIDEO_TRANSFER_BT2020_12 and GST_VIDEO_TRANSFER_BT2020_10 will be mapped to V4L2_XFER_FUNC_709. Need check input caps when map V4L2_XFER_FUNC_709 back to GST_VIDEO_TRANSFER_BT2020_12 and GST_VIDEO_TRANSFER_BT2020_10
Fixes: #816 (closed)