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/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index a7842c5..e2d3b758 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1106,13 +1106,12 @@
 	return ret;
 }
 
-int ipv6_dev_get_saddr(struct net_device *dst_dev,
+int ipv6_dev_get_saddr(struct net *net, struct net_device *dst_dev,
 		       const struct in6_addr *daddr, unsigned int prefs,
 		       struct in6_addr *saddr)
 {
 	struct ipv6_saddr_score scores[2],
 				*score = &scores[0], *hiscore = &scores[1];
-	struct net *net = dev_net(dst_dev);
 	struct ipv6_saddr_dst dst;
 	struct net_device *dev;
 	int dst_type;