UNUSED variable from service reference is now used as buffer flag for gstreamer

REFTYPE:FLAGS:STYPE:SID:TSID:ONID:NS:PARENT_SID:PARENT_TSID:UNUSED
D D X X X X X X X X
4097:0:1:0:0:0:0:0:0:0:URL:NAME (no buffering)
4097:0:1:0:0:0:0:0:0:1:URL:NAME (buffering enabled)
4097:0:1:0:0:0:0:0:0:3:URL:NAME (progressive download and buffering enabled)

Progressive download requires buffering enabled, so it's mandatory to use flag 3 not 2