xfrm6: ensure to use the same dev when building a bundle

When building a bundle, we set dst.dev and rt6.rt6i_idev.
We must ensure to set the same device for both fields.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index ae18165..00bf7c9 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -124,7 +124,7 @@
 	xdst->u.dst.dev = dev;
 	dev_hold(dev);
 
-	xdst->u.rt6.rt6i_idev = in6_dev_get(rt->u.dst.dev);
+	xdst->u.rt6.rt6i_idev = in6_dev_get(dev);
 	if (!xdst->u.rt6.rt6i_idev)
 		return -ENODEV;