android/hal-a2dp: Add missing a2dp handler introduced in Android 5
android/hal-a2dp: Add missing a2dp handler introduced in Android 5

This is added just to be fair with the IPC mechanism and this callback
should never be called by A2DP Source. It is valid for Sink role only.

ComputeCycles/bluez,silent-snowman/bluez,pkarasev3/bluez,ComputeCycles/bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,silent-snowman/bluez,silent-snowman/bluez,ComputeCycles/bluez,mapfau/bluez,pkarasev3/bluez,ComputeCycles/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,pkarasev3/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez