audio policy: move output handle to AudioOutputDescriptor base class

Output handle of AudioOutputDescriptor is required by derived
implementation of some AudioPolicyManager methods.
These methods need to access attributes of an output which is not
accessible through AudioOutputDescriptor base class unless output
handle is made available here.

Change-Id: I96ef9fd1c5a94874acb897245501ba2f9c9ab0c0
2 files changed