Floss: Wire A2DP Sink missing callbacks to floss topshim

Some a2dp sink callbacks are missing the wiring. This crash the daemon
when a peer connect to our a2dp sink profile.

Bug: 264745185
Test: run AVRCP/CT/PTH/BV-01-C along with the top of this series
Tag: #floss

Change-Id: I6759daf9e3c28df039e783d9375b5f04a14774c9