[ovn-vif] Issue with connecting PF representor of DPU to OVN

[Ihtisham ul Haq]

We are using baremetal with Nvidia Bluefield 2 DPU with the goal of connecting the host(without any VMs) to the OVN overlay. But we can't connect PF representor to the overlay because as per docs[0] if we don't have VF representor but rather PF representor, as we want to connect the baremetal host directly to the OVN, we don't need to provide `vf-num` but the code[1] expects to have this key, otherwise the ovn-controller can't claim the port.

[0] https://github.com/ovn-org/ovn-vif/blob/main/Documentation/topics/vif-plug-providers/vif-plug-representor.rst
[1] https://github.com/ovn-org/ovn-vif/blob/731e0995719fe3e96a4fa6423bdbd4a0ccb8b8ea/lib/vif-plug-providers/representor/vif-plug-representor.c#L739