parse: improve H.264 parser for reusage
parse: improve H.264 parser for reusage

We don't want to update the global values until the parsing succeeds.

Signed-off-by: Felipe Contreras <de77a8b9cd239b204c19c52ed62e48ab47243362@nokia.com>

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