relax dns/gateway/netmask when sdn enabled
relax dns/gateway/netmask when sdn enabled

When creating a service with SDN enabled, options
--dns, --gateway, --netmask are not used.

Change-Id: I5dbc4a65e60e051740ab49d2c2c4624f7b915afc

vmware/photon-controller-cli,vmware/photon-controller-cli