AudioManager: optimize audio port listener registration

In order to reduce the number of binder calls, only install an
audio port callback in a client process if either:
- an audio port related API has been called once
- an audio port listenr has been registered.

Bug: 22045560.
Change-Id: I0e5cf31bec0c986d6f7761891b860ba6fadd2f4c
1 file changed