arp: fix unused variable warnning when CONFIG_PROC_FS=n

net/ipv4/arp.c:1412:36: warning: unused variable 'arp_seq_ops' [-Wunused-const-variable]

Add #ifdef CONFIG_PROC_FS for 'arp_seq_ops'.

Fixes: e968b1b3 ("arp: Remove #ifdef CONFIG_PROC_FS")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/arp.c

@@ -1304,9 +1304,9 @@ static struct packet_type arp_packet_type __read_mostly = {
 	.func =	arp_rcv,
 };
 
+#ifdef CONFIG_PROC_FS
 #if IS_ENABLED(CONFIG_AX25)
 
-/* ------------------------------------------------------------------------ */
 /*
  *	ax25 -> ASCII conversion
  */
@@ -1412,16 +1412,13 @@ static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
 	return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
 }
 
-/* ------------------------------------------------------------------------ */
-
 static const struct seq_operations arp_seq_ops = {
 	.start	= arp_seq_start,
 	.next	= neigh_seq_next,
 	.stop	= neigh_seq_stop,
 	.show	= arp_seq_show,
 };
-
-/* ------------------------------------------------------------------------ */
+#endif /* CONFIG_PROC_FS */
 
 static int __net_init arp_net_init(struct net *net)
 {