netfilter: conntrack: remove leftover binary sysctl define

Users got removed in f8572d8f ("sysctl net: Remove unused binary
sysctl code").
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_standalone.c

@@ -489,8 +489,6 @@ static struct ctl_table nf_ct_sysctl_table[] = {
 	{ }
 };
 
-#define NET_NF_CONNTRACK_MAX 2089
-
 static struct ctl_table nf_ct_netfilter_table[] = {
 	{
 		.procname	= "nf_conntrack_max",