Bluetooth: Adding HCI Dev lock for set_active and set_sniff routines.  When data transfer is in progress on a ACL connection, all the time the set_active_mode API will be called to update the timer for next sniff mode. If there is ACL disconnect triggered from remote side, there is possibility of hci connection delete when set_active routine in progress. Found a condition where delete API destroyed the wake lock, which is used in set_active API. In codition leads to crash in set_wakelock API. The current change is to lock hdev, before set_active and set_sniff APIs are called. This avoids the race condition in accessing hci connection, while delete in progress and vice versa.