qeth: l3 fix build error in ipv6 addr list handling

Adapt qeth l3 to:
commit c2e21293
(ipv6: convert addrconf list to hlist)
converted lst_next member of inet6_ifaddr struct to a hlist.
Signed-off-by: NFrank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_l3_main.c

@@ -1928,7 +1928,7 @@ static void qeth_l3_free_vlan_addresses6(struct qeth_card *card,
 	in6_dev = in6_dev_get(vlan_group_get_device(card->vlangrp, vid));
 	if (!in6_dev)
 		return;
-	for (ifa = in6_dev->addr_list; ifa; ifa = ifa->lst_next) {
+	list_for_each_entry(ifa, &in6_dev->addr_list, if_list) {
 		addr = qeth_l3_get_addr_buffer(QETH_PROT_IPV6);
 		if (addr) {
 			memcpy(&addr->u.a6.addr, &ifa->addr,