Bluetooth: Terminate the link if pairing is cancelled

If user decides to cancel the ongoing pairing process (e.g. by clicking
the cancel button on pairing/passkey window), abort any ongoing pairing
and then terminate the link if it was created because of the pair
device action.

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