Bluetooth: Refactor HCI connection code

hci_connect() is a very simple and useless wrapper of hci_connect_acl
and hci_connect_le functions. Addtionally, all places where hci_connect
is called the link type value is passed explicitly. This way, we can
safely delete hci_connect, declare hci_connect_acl and hci_connect_le
in hci_core.h and call them directly.

No functionality is changed by this patch.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>