Bluetooth: Fix LE pairing completion on connection failure

For BR/EDR pairing is assumed to be finished when connection is
done. For LE if connection is successful it did not necessarily
mean that pairing is also done but if the connection is unsuccessful
it should be assumed that pairing procedure is also finished.
This patch registers a new function with connect_cfm_cb callback for
LE link which sends the pairing complete signal to user space if
connection is unsuccessful.

Signed-off-by: Vishal Agarwal <vishal.agarwal@stericsson.com>
Acked-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>