Installer: Don't allow provisioning network configuration when provisioning network is Disabled

An install-config like this is currently allowed:

platform: 
  baremetal: 
    provisioningNetwork: Disabled
    clusterProvisioningIP: 1.2.3.4

However this will not work - the metal3 services will wait forever for the specified IP to come up on the host running the metal3 pod.

For some time we've [disabled the initContainer](https://github.com/openshift/cluster-baremetal-operator/pull/165) that runs [set-static-ip](https://github.com/openshift/ironic-static-ip-manager) so the IP will never become active

We should add validation to the installer so this combination is not allowed