vswitch: Work in terms of ODP port numbers.

vswitch: Work in terms of ODP port numbers.

The vswitch used to be an OpenFlow client, so all of its internals were in
terms of OpenFlow port numbering.  When it was converted to be a datapath
client instead, a shim layer that converted between OpenFlow and ODP port
numbering was inserted, so that it could still work internally in terms of
OpenFlow port numbers.

This commit makes the vswitch use ODP port numbering internally, removing
this shim layer.