audio: fix unresolved link error for javadoc

- Remove @link comments for extended audio
  formats to fix unresolved link error while
  compiling Javadoc
- These extended audio formats are not standard
  AOSP definition and should not be updated for
  javadoc

Change-Id: I34fec0d9709a7def0f92660b6ec0a8e971529161
Move media player list management to Audioservice

Move media player list management to Audioservice so that
list is retained even after BT restart.

Change-Id: Ia2455e6def1900b4af2225c50e1b5325a7ce1a98