netfilter: use PTR_ERR_OR_ZERO()

Fix ptr_ret.cocci warnings:

  net/netfilter/xt_connlimit.c:96:1-3: WARNING: PTR_ERR_OR_ZERO can be used
  net/netfilter/nft_numgen.c:240:1-3: WARNING: PTR_ERR_OR_ZERO can be used

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_numgen.c

@@ -237,10 +237,8 @@ static int nft_ng_random_map_init(const struct nft_ctx *ctx,
 	priv->map = nft_set_lookup_global(ctx->net, ctx->table,
 					  tb[NFTA_NG_SET_NAME],
 					  tb[NFTA_NG_SET_ID], genmask);
-	if (IS_ERR(priv->map))
-		return PTR_ERR(priv->map);
 
-	return 0;
+	return PTR_ERR_OR_ZERO(priv->map);
 }
 
 static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr)

net/netfilter/xt_connlimit.c

@@ -93,10 +93,8 @@ static int connlimit_mt_check(const struct xt_mtchk_param *par)
 
 	/* init private data */
 	info->data = nf_conncount_init(par->net, par->family, keylen);
-	if (IS_ERR(info->data))
-		return PTR_ERR(info->data);
 
-	return 0;
+	return PTR_ERR_OR_ZERO(info->data);
 }
 
 static void connlimit_mt_destroy(const struct xt_mtdtor_param *par)