PBAP: Disconnect PBAP profile only if connected

This patch is needed to handle the PBAP cases for multicast scenarios.
This change will let the disconnection of the PBAP profile with that
remote device only which was actually connected via PBAP among all the
BT connected devices.

Change-Id: I76f6215d1d407d789654e78e448aea5324816a71
CRs-Fixed: 843160