netfilter: nfnetlink_queue: silence bogus compiler warning

net/netfilter/nfnetlink_queue.c:601:36: warning: variable 'ctinfo' is
uninitialized when used here [-Wuninitialized]
   if (ct && nfnl_ct->build(skb, ct, ctinfo, NFQA_CT, NFQA_CT_INFO) < 0)

ctinfo is only uninitialized if ct == NULL.  Init it to 0 to silence this.
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nfnetlink_queue.c

@@ -387,7 +387,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	struct net_device *indev;
 	struct net_device *outdev;
 	struct nf_conn *ct = NULL;
-	enum ip_conntrack_info ctinfo;
+	enum ip_conntrack_info ctinfo = 0;
 	struct nfnl_ct_hook *nfnl_ct;
 	bool csum_verify;
 	char *secdata = NULL;