PlayerBase: remove dead code for OP_PLAY_AUDIO

Remove dead code that was used to monitor OP_PLAY_AUDIO and react
to updates. This client-side  functionality was replaced with
enforcement in AudioFlinger.

Bug: 159749892
Test: removal of dead code, only "m"
Change-Id: I680aa38fecdf7bd062ff31ad35234e4a378059ea