HLS: getDuration should return -1 for live streams

According to the MediaPlayer API documentation -1 should
be returned if the duration is not available. But for HLS 0
is returned. Change this.

Change-Id: Ib7704a94ac8dc104ceed4da4491f0d03cb8f4560
Merge "HLS: getDuration should return -1 for live streams" into du44