audio: Use ChildInterface in StreamCommonImpl

Replace the pair of 'shared_ptr<>, Binder' with
the equivalent ChildInterface.

Fix logging of returned sub-objects to print their
Binder value instead of the local pointer.

Bug: 264712385
Test: m
Change-Id: I1350e7b3720c6244cd8527e1d021ee9577399291
4 files changed