Bluetooth: Make HCI call directly into SCO and L2CAP event functions

The struct hci_proto and all related register/unregister and dispatching
code was removed. HCI core code now call directly the SCO and L2CAP
event functions.

Signed-off-by: Ulisses Furquim <ulisses@profusion.mobi>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>