Bluetooth: Fix LE connection timeout deadlock

The le_conn_timeout() may call hci_le_conn_failed() which in turn may
call hci_conn_del(). Trying to use the _sync variant for cancelling the
conn timeout from hci_conn_del() could therefore result in a deadlock.
This patch converts hci_conn_del() to use the non-sync variant so the
deadlock is not possible.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org # 3.16.x

net/bluetooth/hci_conn.c

@@ -518,7 +518,7 @@ int hci_conn_del(struct hci_conn *conn)
 		/* Unacked frames */
 		hdev->acl_cnt += conn->sent;
 	} else if (conn->type == LE_LINK) {
-		cancel_delayed_work_sync(&conn->le_conn_timeout);
+		cancel_delayed_work(&conn->le_conn_timeout);
 
 		if (hdev->le_pkts)
 			hdev->le_cnt += conn->sent;