DeviceDescriptorBase parcels to media::AudioPort

It has been determined that all of the subclasses of AudioPort need to
be parceled into media::AudioPort rather than having their own type,
similar to how they correspond to the audio_port_v7 struct.

Test: Audio-related CTS tests from CtsMediaTestCases
Change-Id: I971d9dec990ae7d065a74952f63fa9cb7fed236c