Bluetooth: Refactor ACL connection into its own function

The hci_connect() function was starting to get too complicated to be
quickly understood. We can separate the creation of a new ACL
connection into its own function.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>