vdec: improve H.263 args
vdec: improve H.263 args

Signed-off-by: Juha Alanen <8ab7f425f2cbc5dd90719519dddbb1f53425a476@nokia.com>

felipec/gst-dsp,community-ssu/gst-dsp,felipec/gst-dsp,community-ssu/gst-dsp,community-ssu/gst-dsp