Fix for the virhs user creation
Fix for the virhs user creation

Fixed undefined error which can raise when
overcloud_nodes list is empty or undefined.

Change-Id: I9abf3c302486ba3d44a7455b9dde734ee548a5a7

okolisny/InfraRed,redhat-openstack/infrared,redhat-openstack/infrared,okolisny/InfraRed,redhat-openstack/infrared,okolisny/InfraRed