netns: Add network namespace argument to rt6_fill_node() and ipv6_dev_get_saddr()

ipv6_dev_get_saddr() blindly de-references dst_dev to get the network
namespace, but some callers might pass NULL.  Change callers to pass a
namespace pointer instead.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index bc391ba..5f53db7 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -107,6 +107,7 @@
 {
 	struct sk_buff *skb;
 	struct netlink_callback *cb;
+	struct net *net;
 };
 
 extern int rt6_dump_route(struct rt6_info *rt, void *p_arg);