Since [1], "get_vif_port_by_id" is also returning ports with an
invalid ofport. OVS firewall cannot set an OpenFlow rule for a port
without a valid ofport. "get_ovs_port" should filter out those ports.
Related-Bug: #1815989
Related-Bug: #1734320
[1]https://review.opendev.org/#/c/640258/
Change-Id: Id12486b3127ab4ac8ad9ef2b3641da1b79a25a50