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/ip6_output.c b/net/ipv6/ip6_output.c
index a4402de..0e844c2 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -934,7 +934,7 @@
 		goto out_err_release;
 
 	if (ipv6_addr_any(&fl->fl6_src)) {
-		err = ipv6_dev_get_saddr(ip6_dst_idev(*dst)->dev,
+		err = ipv6_dev_get_saddr(net, ip6_dst_idev(*dst)->dev,
 					 &fl->fl6_dst,
 					 sk ? inet6_sk(sk)->srcprefs : 0,
 					 &fl->fl6_src);