The nsx-v backend does not suport adding a route where the
nexthop is part of the destination.
This patch skips it (instead of failing at the backend)
and also skips a tempest test that tries the same thing
The nsx backend does not allow adding different static DHCP bindings
with the same mac, so an instance cannot be deployed with a port with
This patch prevent create/update of a port with more than 1 fixed ip.