[IPV6] ADDRCONF: Convert addrconf_lock to RCU.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index e459e1a..34489c1 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -189,6 +189,7 @@
 	struct ipv6_devconf	cnf;
 	struct ipv6_devstat	stats;
 	unsigned long		tstamp; /* ipv6InterfaceTable update timestamp */
+	struct rcu_head		rcu;
 };
 
 extern struct ipv6_devconf ipv6_devconf;