Bluetooth-OPP: Avoid calling incoming notification if already notified

This change will ensure that incoming notification will not be shown
again if its already displayed. Otherwise, if there is an ongoing
transfer updatenotification thread will be called every 1 sec which
will update the pendingnotification even if its already notified.

Cleaning up Tx/Rx sessions if user abort occurs. Otherwise, cleanup
happens only transfer is successful this may cause Tx/Rx failure.

CRs-Fixed: 653842
Change-Id: Ifc1335849914f3032459117836473e0cd443060f