dvdplayer: don't constantly hammer demuxer to get stream count

Note this could cause regressions in files where streams show
up during playback, but i think the demuxer signals such
situations now.

xbmc/cores/dvdplayer/DVDPlayer.cpp

@@ -2799,8 +2799,6 @@ float CDVDPlayer::GetSubTitleDelay()
 // priority: 1: libdvdnav, 2: external subtitles, 3: muxed subtitles
 int CDVDPlayer::GetSubtitleCount()
 {
-  StreamLock lock(this);
-  m_SelectionStreams.Update(m_pInputStream, m_pDemuxer);
   return m_SelectionStreams.Count(STREAM_SUBTITLE);
 }
 
@@ -2852,8 +2850,6 @@ void CDVDPlayer::SetSubtitleVisible(bool bVisible)
 
 int CDVDPlayer::GetAudioStreamCount()
 {
-  StreamLock lock(this);
-  m_SelectionStreams.Update(m_pInputStream, m_pDemuxer);
   return m_SelectionStreams.Count(STREAM_AUDIO);
 }