Grant provider access to status subresource in clusters (openshift#177)

Currently when provider tries to update cluster status, it gets error:

  User "system:serviceaccount:openstack-provider-system:default" cannot update resource "clusters/status" in API group "cluster.k8s.io" in the namespace "default"

This happens because "status" is separate subresource and access to it
must be granted separately.

config/rbac/rbac_role.yaml

@@ -19,6 +19,7 @@ rules:
   - cluster.k8s.io
   resources:
   - clusters
+  - clusters/status
   - machines
   - machinedeployments
   - machinesets