sctp: Guard IPV6 specific code properly.

Outside of net/sctp/ipv6.c, IPV6 specific code needs to
be ifdef guarded.

This fixes build failures with IPV6 disabled.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/protocol.c

@@ -637,6 +637,7 @@ void sctp_addr_wq_timeout_handler(unsigned long arg)
 		    " for cmd %d at entry %p\n", &sctp_addr_waitq, &addrw->a, addrw->state,
 		    addrw);
 
+#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
 		/* Now we send an ASCONF for each association */
 		/* Note. we currently don't handle link local IPv6 addressees */
 		if (addrw->a.sa.sa_family == AF_INET6) {
@@ -659,7 +660,7 @@ void sctp_addr_wq_timeout_handler(unsigned long arg)
 				break;
 			}
 		}
-
+#endif
 		list_for_each_entry(sp, &sctp_auto_asconf_splist, auto_asconf_list) {
 			struct sock *sk;