playbook: Fix missing iptables reset

playbook/roles/olimex-board/templates/iptables.j2

@@ -7,6 +7,7 @@ echo "Update firewall. Close all ports except SSH ports."
 
 # Remove all existing rules
 iptables -F
+ip6tables -F
 
 # Allow SSH access
 iptables -A INPUT -p tcp --dport 22 -j ACCEPT