secchan: Switch in-band control traffic by hand only on OpenFlow TCP ports.

secchan: Switch in-band control traffic by hand only on OpenFlow TCP ports.

To run services, other than the controller itself, on the same IP and MAC
as the controller, sophisticated controllers such as NOX need to have some
insight into the controller's location, etc.  Before this commit, this
was not possible, because any traffic to or from the controller's MAC
address was switched "by hand" by secchan, without involving the controller
at all.

After this commit, only traffic to or from the controller's MAC *and on
the OpenFlow TCP or SSL port* is switched by hand, which should fix the
problem.