netfilter: nfnetlink_log: silence bogus compiler warning

net/netfilter/nfnetlink_log.c:800:18: warning: variable 'ctinfo' is uninitialized

The warning is bogus, the variable is only used if ct is non-NULL and
always initialised in that case.  Init to 0 too to silence this.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202309100514.ndBFebXN-lkp@intel.com/Signed-off-by: Florian Westphal <fw@strlen.de>

net/netfilter/nfnetlink_log.c

@@ -698,8 +698,8 @@ nfulnl_log_packet(struct net *net,
 	unsigned int plen = 0;
 	struct nfnl_log_net *log = nfnl_log_pernet(net);
 	const struct nfnl_ct_hook *nfnl_ct = NULL;
+	enum ip_conntrack_info ctinfo = 0;
 	struct nf_conn *ct = NULL;
-	enum ip_conntrack_info ctinfo;
 
 	if (li_user && li_user->type == NF_LOG_TYPE_ULOG)
 		li = li_user;