Fix all invalid IPs in the iptables nat file

Modify fixaddr to check every entry in the nat rules file instead of
just looking at the last entry.

(cherry picked from commit 5b51bf83ac993491d9e71ba259b72525b53984a1)
Merge pull request #4094 from ncdc/stage-fix-all-invalid-iptables-ips

Merged by openshift-bot