Add loop_control and loop_var to silence a warning

The CentOS tasks run inside of a loop in tasks/main.yaml. That means
that item has been defined in the loop there. While it's currently
working, go ahead and add loop_control.loop_var to remove the clash.

Change-Id: I0e8288c35645945aa9b43fb02c29576c1ad31d7e

playbooks/roles/base-repos/tasks/CentOS.yaml

@@ -8,11 +8,13 @@
 # restart the daemon for good measure after it is upgraded.
 - name: Install latest selinux-policy and systemd
   yum:
-    name: "{{ item }}"
+    name: "{{ package_item }}"
     state: latest
   loop:
     - selinux-policy
     - systemd
+  loop_control:
+    loop_var: package_item
   register: systemd_updated
 
 - name: Restart systemd