[IPV6]: ROUTE: Add support for Router Preference (RFC4191).

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 01acca0..5016132 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -87,7 +87,8 @@
 extern struct rt6_info *	rt6_get_dflt_router(struct in6_addr *addr,
 						    struct net_device *dev);
 extern struct rt6_info *	rt6_add_dflt_router(struct in6_addr *gwaddr,
-						    struct net_device *dev);
+						    struct net_device *dev,
+						    unsigned int pref);
 
 extern void			rt6_purge_dflt_routers(void);