IAudioFlinger: create Audio Policy Service before calling AudioFlinger

Make sure we connect to Audio Policy Service before calling into AudioFlinger
implementation to avoid the following deadlock
 1) AudioFlinger locks its global mutex and calls into Audio Policy Service
 2) If this is the first time Audio Policy Service is queried from inside
    audioserver process this will trigger Audio Policy Manager initialization.
 3) Audio Policy Manager initialization calls into AudioFlinger which will
    try to lock its global mutex
    => Deadlock

Bug: 167155843
Test: manual audioserver crash test
Change-Id: Ic30fc4dd460f4a3ce64bc43c5aa58cddff3bd707