Allow to set custom repo via overrides.yml

Update aio and ironic cluster models to allow add custom repo.

Change-Id: Ica43ace3e7e8d5f1e00a8810df6040def90d7bfb
diff --git a/classes/cluster/virtual-mcp11-ovs-ironic/init.yml b/classes/cluster/virtual-mcp11-ovs-ironic/init.yml
index 23d2566..531d59a 100644
--- a/classes/cluster/virtual-mcp11-ovs-ironic/init.yml
+++ b/classes/cluster/virtual-mcp11-ovs-ironic/init.yml
@@ -44,3 +44,11 @@
     openstack_baremeta_neutron_subnet_allocation_start: 192.168.90.100
     openstack_baremeta_neutron_subnet_allocation_end: 192.168.90.150
     openstack_baremetal_node01_hostname: bmt01
+  linux:
+    system:
+      repo:
+        linux_system_repo:
+          source: ${_param:linux_system_repo}
+          architectures: amd64
+          clean_file: true
+