SAP: Remove sdp record while BT is being turned off to prevent leak

Remove sdp record created dynamically for SAP server during BT off state.
Without this call, there is leak in sdp layer in stack as sdp record is
never removed, even though the socket is closed.
Also proper checks are added to prevent call to remove sdp record when
adapter is null.

Change-Id: I739cc3115f6cd7fedf9085e8522c96da257e9568