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-aio/init.yml b/classes/cluster/virtual-mcp11-aio/init.yml
index af3fdfc..d0c5f40 100755
--- a/classes/cluster/virtual-mcp11-aio/init.yml
+++ b/classes/cluster/virtual-mcp11-aio/init.yml
@@ -43,6 +43,11 @@
           enabled: true
           # r00tme
           password: $6$9ojWyyN.$26Vj46JtCUL6C7XBQ8RmQTZLwo8/8SkqTRElXh0X2YBLrt7E/aVe2AYQ5gguYUwUknZNOSn5q7M9M3Jyf2gof/
+      repo:
+        linux_system_repo:
+          source: ${_param:linux_system_repo}
+          architectures: amd64
+          clean_file: true
     network:
       bridge: openvswitch
       interface: