Display IPMI ip address fallback

If you deploy the IPMI functionality after discovery you get no bmc
address displayed on the node detail page. With this fix we always
display as a fallback the network section entry as for other ip's too.

For further fixing like the crowbar wall link list we will try to plan that in an upcoming sprint.
Hrm. Are you sure this is correct? If it's not in the crowbar wall, then I think it's not been configured by the IPMI barclamp, so the address doesn't work.