demux: ts: don't compute pcr offset from non video/audio
demux: ts: don't compute pcr offset from non video/audio

refs #17148

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc