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>
        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)
 
 
        /* 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)