Bluetooth: L2CAP: Introduce CoC channel states

Adds CoC channel's context to hold channel setup state and SM routine
that evaluates validness of transitions.
At the beginning DISCONNECTED, CONNECT and CONFIG states are added and
used by CoC setup on BR/EDR transport.

Change-Id: I1bbd16ec2f59ea961791786b78f22834d6f4b4d8
Signed-off-by: Arkadiusz Lichwa <arkadiusz.lichwa@tieto.com>