MFC r290018: Reimplement enable and implement disable of virtual ports.

Now on 24xx and above chips it is really possible to simulate several
virtual FC ports with single physical one. For example, it allows to
configure several targets in ctl.conf, assign each of them to separate
virtual port, and let user to control access to them with switch zoning.

I still doubt that all problems are solved there, but at now it passes
at least basic tests.