SAP: Prevent leak during turn off BT

Use Case:
1. Initiate SAP connection and disconnection from Remote Device.
2. Do this for 3-4 times
3. Do BT off, and check logs.

Error leak:
JHwRemoteBinder: BinderProxy is being destroyed but the application did not call unlinkToDeath to
   unlink all of its death recipients beforehand.  Releasing leaked death recipient:
   com.android.bluetooth.sap.SapRilReceiver$SapProxyDeathRecipient
BluetoothAdapterService: handleMessage() - Message: 1
BluetoothAdapterService: handleMessage() - MESSAGE_PROFILE_SERVICE_STATE_CHANGED
BluetoothAdapterService: processProfileServiceStateChanged() - serviceName=com.android.bluetooth.
 sap.SapService isTurningOn=false isTurningOff=true isBleTurningOn=false isBleTurningOff=false

Failure:
"Observed SAP Binder related leaks in log cat logs".

Fix:
Unlink previously linked death notification to avoid leak
in profile

Test: Checked after the above usecase to see if no memory leak error is seen in logs.

Bug: 62412151
Change-Id: Ic2a4d96c0a30c45eca08a65921693b386a193d69