bluetooth: Fix SCO connection synchronization.

Configure the alternate setting of interface '1' to
'2' once the BT USB driver gets the SCO connection complete
event from HCI Layer. Similarly, configure the alt. setting
to '0' on SCO disconnection complete event.

Change-Id: Ia1384451bedda52749599516e9ff4ec3b1f409c7
Signed-off-by: Nitin Srivastava <nitinsr@codeaurora.org>