netfilter: conntrack: remove unused netns_ct member

since 23014011ba ('netfilter: conntrack: support a fixed size of 128 distinct labels')
this isn't needed anymore.

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

include/net/netns/conntrack.h

@@ -91,7 +91,6 @@ struct netns_ct {
 	struct nf_ip_net	nf_ct_proto;
 #if defined(CONFIG_NF_CONNTRACK_LABELS)
 	unsigned int		labels_used;
-	u8			label_words;
 #endif
 };
 #endif