FWaaS V2 cannot be supported for distributed routers since the
FW rules are on the PLR, but only the TLR has the subnets interfaces.
This patch adds a partial support, assuming all interface ports
have the same policy & rules (as it was in FWaaSv1) by ignoring the vnic-id.
This way customers with distributed routers can migrate to FWaaS v2.
Change-Id: Ieaaf4149d5daa07341effdc480ae453a67d5b6bb