netfilter: nft_limit: Clone packet limits' cost value

When cloning a packet-based limit expression, copy the cost value as
well. Otherwise the new limit is not functional anymore.

Fixes: 3b9e2ea6c11bf ("netfilter: nft_limit: move stateful fields out of expression data")
Signed-off-by: Phil Sutter <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/nft_limit.c

···
 	struct nft_limit_priv_pkts *priv_dst = nft_expr_priv(dst);
 	struct nft_limit_priv_pkts *priv_src = nft_expr_priv(src);
 
+	priv_dst->cost = priv_src->cost;
+
 	return nft_limit_clone(&priv_dst->limit, &priv_src->limit);
 }