secchan: Implement in-band control using wildcard rules.

secchan: Implement in-band control using wildcard rules.

Until now, there has been a problem with flows set up by the controller
overriding in-band control decisions: if the controller sets up, say, a
flow that matches every packet, then the in-band control flow miss handler
will never be called, and the connection to the controller may well fail.

This commit fixes the problem by implementing in-band control in terms
of wildcard rules that have a higher priority than any rule that can be
set up by the OpenFlow controller.

This should also fix the issue that in-band control does not respect VLANs
and other structure set up by the vswitch, since the rules set up by
in-band control use OFPP_NORMAL.