netfilter: nft_lookup: update element stateful expression

If the set element comes with an stateful expression, update it.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_lookup.c

@@ -43,6 +43,7 @@ void nft_lookup_eval(const struct nft_expr *expr,
 		nft_data_copy(&regs->data[priv->dreg],
 			      nft_set_ext_data(ext), set->dlen);
 
+	nft_set_elem_update_expr(ext, regs, pkt);
 }
 
 static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {