skins2: fix typo following a recent change in playlist.
skins2: fix typo following a recent change in playlist.

This caused the skin engine to fail to refresh on the spot when new items
were added to the playlist.

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