netfilter: nf_conntrack: checking for IS_ERR() instead of NULL

We recently changed this from nf_conntrack_alloc() to nf_ct_tmpl_alloc()
so the error handling needs to changed to check for NULL instead of
IS_ERR().

Fixes: 0838aa7f ('netfilter: fix netns dependencies with conntrack templates')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_synproxy_core.c

@@ -353,10 +353,8 @@ static int __net_init synproxy_net_init(struct net *net)
 	int err = -ENOMEM;
 
 	ct = nf_ct_tmpl_alloc(net, 0, GFP_KERNEL);
-	if (IS_ERR(ct)) {
-		err = PTR_ERR(ct);
+	if (!ct)
 		goto err1;
-	}
 
 	if (!nfct_seqadj_ext_add(ct))
 		goto err2;

net/netfilter/xt_CT.c

@@ -202,9 +202,10 @@ static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 		goto err1;
 
 	ct = nf_ct_tmpl_alloc(par->net, info->zone, GFP_KERNEL);
-	ret = PTR_ERR(ct);
-	if (IS_ERR(ct))
+	if (!ct) {
+		ret = -ENOMEM;
 		goto err2;
+	}
 
 	ret = 0;
 	if ((info->ct_events || info->exp_events) &&