netfilter: nft_set_hash: skip fixed hash if timeout is specified

Fixed hash supports to timeouts, so skip it. Otherwise, userspace hits
EOPNOTSUPP.

Fixes: 6c03ae21 ("netfilter: nft_set_hash: add non-resizable hashtable implementation")
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_set_hash.c

@@ -674,7 +674,7 @@ static const struct nft_set_ops *
 nft_hash_select_ops(const struct nft_ctx *ctx, const struct nft_set_desc *desc,
 		    u32 flags)
 {
-	if (desc->size) {
+	if (desc->size && !(flags & NFT_SET_TIMEOUT)) {
 		switch (desc->klen) {
 		case 4:
 			return &nft_hash_fast_ops;