Enabling xt_u32 in Openshift Container Platform 4

Issue

Module xt_u32 is not available out of the box on rhcos nodes and can't be used in a pod definition such as the following one:

apiVersion: v1
kind: Pod
metadata:
  name: centos-pod
  labels:
    name: centos-pod
spec:
  containers:
  - name: centos-pod
    command: ["/bin/sh", "-c"]
    args:
        ["yum install -y iptables && sleep inf"]
    image: centos:latest
    securityContext:
      capabilities:
        add: ["NET_ADMIN"]