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

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

[ Upstream commit 191cd582500f49b32a63040fedeebb0168c720af ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>