hlsdemux2: Don't set a referer when updating playlists
In the same way we don't for regular playlists in the base class.
If there is a referer specified by the app/user, the downloadhelper will set it accordingly.
Fixes playing back https://ntv1.akamaized.net/hls/live/2014075/NASA-NTV1-HLS/master_2000.m3u8 or directly the master playlist : https://ntv1.akamaized.net/hls/live/2014075/NASA-NTV1-HLS/master.m3u8
Edited by Edward Hervey