Bluetooth: Fix hci_conn timeout routine

If occurs a LE or SCO hci_conn timeout and the connection is already
established (BT_CONNECTED state), the connection is not terminated as
expected. This bug can be reproduced using l2test or scotest tool.
Once the connection is established, kill l2test/scotest and the
connection won't be terminated.

This patch fixes hci_conn_disconnect helper so it is able to
terminate LE and SCO connections, as well as ACL.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>