netfilter: nf_tables: prefer nft_trans_elem_alloc helper

Reduce references to sizeof(struct nft_trans_elem).
Preparation patch to move this to a flexiable array to store
elem references.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Author: Florian Westphal

net/netfilter/nf_tables_api.c

@@ -6409,7 +6409,7 @@ static void nf_tables_setelem_notify(const struct nft_ctx *ctx,
 	nfnetlink_set_err(net, portid, NFNLGRP_NFTABLES, -ENOBUFS);
 }
 
-static struct nft_trans *nft_trans_elem_alloc(struct nft_ctx *ctx,
+static struct nft_trans *nft_trans_elem_alloc(const struct nft_ctx *ctx,
 					      int msg_type,
 					      struct nft_set *set)
 {
@@ -7471,13 +7471,11 @@ static int __nft_set_catchall_flush(const struct nft_ctx *ctx,
 {
 	struct nft_trans *trans;
 
-	trans = nft_trans_alloc_gfp(ctx, NFT_MSG_DELSETELEM,
-				    sizeof(struct nft_trans_elem), GFP_KERNEL);
+	trans = nft_trans_elem_alloc(ctx, NFT_MSG_DELSETELEM, set);
 	if (!trans)
 		return -ENOMEM;
 
 	nft_setelem_data_deactivate(ctx->net, set, elem_priv);
-	nft_trans_elem_set(trans) = set;
 	nft_trans_elem_priv(trans) = elem_priv;
 	nft_trans_commit_list_add_tail(ctx->net, trans);