Bluetooth: hci_conn: Fix hci_connect_le_sync

The handling of connection failures shall be handled by the request
completion callback as already done by hci_cs_le_create_conn, also make
sure to use hci_conn_failed instead of hci_le_conn_failed as the later
don't actually call hci_conn_del to cleanup.

Link: https://github.com/bluez/bluez/issues/340


Fixes: 8e8b92ee ("Bluetooth: hci_sync: Add hci_le_create_conn_sync")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>