MediaPlayer2: remove AudioManager private API usage

Private API AudioManager.getDevicesStatic() is being used in
MediaPlayer2 for conversion between id <=> AudioDeviceInfo.
This conversion was added to talk with internal native AudioTrack API,
but in MediaPlayer2 since we will use public java AudioTrack API,
the given AudioDeviceInfo can be directly passed to java AudioTrack
instance.

Test: CtsMediaTestCases:android.media.cts.RoutingTest
Bug: 112767549
Change-Id: I9aeae02202edb6b5f0eb72b4f4dd3c936103ced2