Load iscsi_tcp module from the host.

Until now, it's loaded from within the container, this doesn't work
with SELinux separation.

Change-Id: Ia2cd08b9b7950ebca4d75938ae4329641c2d6f7c
Depends-on: Ic9076a0a1a8e1360495dcf0eb766118ec63dc362
Related-Bug: 1794550

docker/services/ironic-conductor.yaml

@@ -193,6 +193,12 @@ outputs:
                 environment:
                   - KOLLA_CONFIG_STRATEGY=COPY_ALWAYS
       host_prep_tasks:
+        - name: load iscsi_tcp module
+          import_role:
+            role: tripleo-module-load
+          vars:
+            modules:
+              - name: iscsi_tcp
         - name: create persistent directories
           file:
             path: "{{ item.path }}"