Bluetooth: Add trust device feature.

Add set trust feature where the remote device is marked
as a trusted device for subsequent connection.

Change-Id: Iee491db2e5b6090761a4f42467ac36ed53923fc4
CRs-fixed: 523135
Bluetooth: Connect only A2dp Sink devices.

DUT supports only A2DP source role,it should connect
only with A2DP sink devices.RENDERING service must be
supported by A2DP sink devices.Hence try to connect A2DP
source only with these class of devices.

CRs-Fixed: 507306

Change-Id: I93d9d30185444473e79008b47b607802ec5e7f3e