decoder: h264: cope with new gst_h264_parser_parse_sei() interface.
decoder: h264: cope with new gst_h264_parser_parse_sei() interface.

The gst_h264_parse_parse_sei() function now returns an array of SEI
messages, instead of a single SEI message. Reason: it is allowed to
have several SEI messages packed into a single SEI NAL unit, instead
of multiple NAL units.

gbeauchesne/gstreamer-vaapi,CapOM/gstreamer-vaapi,CapOM/gstreamer-vaapi,gbeauchesne/gstreamer-vaapi,GStreamer/gstreamer-vaapi,ceyusa/gstreamer-vaapi,01org/iotg-lin-gfx-gstreamer-vaapi,01org/iotg-lin-gfx-gstreamer-vaapi,01org/iotg-lin-gfx-gstreamer-vaapi,gbeauchesne/gstreamer-vaapi,GStreamer/gstreamer-vaapi,CapOM/gstreamer-vaapi,ceyusa/gstreamer-vaapi