Bluetooth: Fix mgmt pairing failure when authentication fails

Whether through HCI with BR/EDR or SMP with LE when authentication fails
we should also notify any pending Pair Device mgmt command. This patch
updates the mgmt_auth_failed function to take the actual hci_conn object
and makes sure that any pending pairing command is notified and cleaned
up appropriately.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>