by using below command you can made VLC play the playlist, here in my case the PL tbbt-s6.xspf is placed on Desktop. Its actually The Big Bang Theory (TBBT)
/usr/bin/vlc --started-from-file /home/navdeep/Desktop/tbbt-s6.xspf
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
 core libvlc: Running vlc with the default interface. Use ‘cvlc’ to use vlc without interface.