Bluetooth: call hci_le_conn_failed with hdev lock in hci_le_conn_failed

hci_le_conn_failed function's documentation says that the caller must
hold hdev->lock. The only callsite that does not hold that lock is
hci_le_conn_failed. The other 3 callsites hold the hdev->lock very
locally. The solution is to hold the lock during the call to
hci_le_conn_failed.

Fixes: 3c857757

 ("Bluetooth: Add directed advertising support through connect()")
Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>