Setting up backend images for VCP VM's

This patchset is required by: #/c/25365/

Change-Id: I2aa73d3f16b10d2d7597a89f46fdeed6bf268661
diff --git a/salt/control/cluster/infra_idm_cluster.yml b/salt/control/cluster/infra_idm_cluster.yml
index ff135a1..f322910 100644
--- a/salt/control/cluster/infra_idm_cluster.yml
+++ b/salt/control/cluster/infra_idm_cluster.yml
@@ -1,4 +1,7 @@
 parameters:
+  _param:
+    salt_control_centos7_image_backend: /var/lib/libvirt/images/backends/centos7.qcow2
+    infra_idm_backend_image: ${_param:salt_control_centos7_image_backend}
   salt:
     control:
       size:
@@ -16,14 +19,17 @@
               name: ${_param:infra_idm_node01_hostname}
               provider: ${_param:infra_kvm_node01_hostname}.${_param:cluster_domain}
               image: ${_param:salt_control_centos7_image}
+              backend: ${_param:infra_idm_backend_image}
               size: infra.idm
             idm02:
               name: ${_param:infra_idm_node02_hostname}
               provider: ${_param:infra_kvm_node02_hostname}.${_param:cluster_domain}
               image: ${_param:salt_control_centos7_image}
+              backend: ${_param:infra_idm_backend_image}
               size: infra.idm
             idm03:
               name: ${_param:infra_idm_node03_hostname}
               provider: ${_param:infra_kvm_node03_hostname}.${_param:cluster_domain}
               image: ${_param:salt_control_centos7_image}
+              backend: ${_param:infra_idm_backend_image}
               size: infra.idm