ipv6: change ipv6_stub_impl.ipv6_dst_lookup to take net argument

This patch adds net argument to ipv6_stub_impl.ipv6_dst_lookup
for use cases where sk is not available (like mpls).
sk appears to be needed to get the namespace 'net' and is optional
otherwise. This patch series changes ipv6_stub_impl.ipv6_dst_lookup
to take net argument. sk remains optional.

All callers of ipv6_stub_impl.ipv6_dst_lookup have been modified
to pass net. I have modified them to use already available
'net' in the scope of the call. I can change them to
sock_net(sk) to avoid any unintended change in behaviour if sock
namespace is different. They dont seem to be from code inspection.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 81f0f24..beed5d4 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2034,7 +2034,7 @@
 		fl6.flowi6_mark = skb->mark;
 		fl6.flowi6_proto = IPPROTO_UDP;
 
-		if (ipv6_stub->ipv6_dst_lookup(sk, &ndst, &fl6)) {
+		if (ipv6_stub->ipv6_dst_lookup(vxlan->net, sk, &ndst, &fl6)) {
 			netdev_dbg(dev, "no route to %pI6\n",
 				   &dst->sin6.sin6_addr);
 			dev->stats.tx_carrier_errors++;