Allocate lcb when connection complete if can't find one

When BT stack sends create connection command and receive connection
request at the same time, connection request will reuse the link control
block created by create connection command. But the link control block
will be released before connection complete due to controller busy.

Bug:112818458
Test: manual - turn on BT and turn on Headset within little time gap
Change-Id: Ie30c655b933250f1709ba10c578ea5f30ea13139