hamradio: bpqether: Fix -Wunused-const-variable warning

If CONFIG_PROC_FS is n, gcc warns:

drivers/net/hamradio/bpqether.c:437:36:
 warning: ‘bpq_seqops’ defined but not used [-Wunused-const-variable=]
 static const struct seq_operations bpq_seqops = {
                                    ^~~~~~~~~~
Use #ifdef macro to gurad this.
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/hamradio/bpqether.c

@@ -368,7 +368,7 @@ static int bpq_close(struct net_device *dev)
 
 /* ------------------------------------------------------------------------ */
 
-
+#ifdef CONFIG_PROC_FS
 /*
  *	Proc filesystem
  */
@@ -440,7 +440,7 @@ static const struct seq_operations bpq_seqops = {
 	.stop = bpq_seq_stop,
 	.show = bpq_seq_show,
 };
-
+#endif
 /* ------------------------------------------------------------------------ */
 
 static const struct net_device_ops bpq_netdev_ops = {