audio: Fix for clip skip issue during SSR

- Specific AAC clips are skipped to next clip on triggering SSR
- When SSR is triggered while track is waiting for stream end event for
  low bit rate clips, drain is unblocked and playback is switched to
  next track
- Fix is not to post drain ready event during SSR as actual stream end
  is not reached with more compressed data buffered to DSP

  CRs-Fixed: 766541

Change-Id: Id1573160001a2a252dc6613b58f70233e77cc3b4