netfilter: nf_tables: restore notifications for anonymous set destruction

Since we have the context available again, we can restore notifications
for destruction of anonymous sets.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nft_lookup.c b/net/netfilter/nft_lookup.c
index 953978e..7fd2bea 100644
--- a/net/netfilter/nft_lookup.c
+++ b/net/netfilter/nft_lookup.c
@@ -94,7 +94,7 @@
 {
 	struct nft_lookup *priv = nft_expr_priv(expr);
 
-	nf_tables_unbind_set(NULL, priv->set, &priv->binding);
+	nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 }
 
 static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)