Move to idle when remote disconnects during connection.

Chrysler Uconnect Touch initiates disconnect for a2dp on
l2cap just after discovery on AVDTP channel, stack does not
send any message to BTIF layer for disconnection, this
causes btif getting stuck in opening state and later no stable
connection update is sent to app. Since it is intermediate
state all subsequent connection trials fails.

Send disconnect event from incoming state to closing state
and then closing state will send proper msg to btif layer. Add
closing msg handling in btif layer so that we can update app
for connection disconnect when initiated from remote and move to
proper stable state for accepting/initiating connection.

Change-Id: I011d9ffe9d721235217320c1e5281f70328c7f13