mt76: remove variable set but not used

The code that uses variable queued has been removed,
and "mt76_is_usb(dev) ? q->ndesc - q->queued : q->queued"
didn't do anything, so all they should be removed as well.

Eliminate the following clang warnings:
drivers/net/wireless/mediatek/mt76/debugfs.c:77:9: warning: variable
‘queued’ set but not used.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Fixes: 2d8be76c ("mt76: debugfs: improve queue node readability")
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wireless/mediatek/mt76/debugfs.c

@@ -74,13 +74,12 @@ EXPORT_SYMBOL_GPL(mt76_queues_read);
 static int mt76_rx_queues_read(struct seq_file *s, void *data)
 {
 	struct mt76_dev *dev = dev_get_drvdata(s->private);
-	int i, queued;
+	int i;
 
 	seq_puts(s, "     queue | hw-queued |      head |      tail |\n");
 	mt76_for_each_q_rx(dev, i) {
 		struct mt76_queue *q = &dev->q_rx[i];
 
-		queued = mt76_is_usb(dev) ? q->ndesc - q->queued : q->queued;
 		seq_printf(s, " %9d | %9d | %9d | %9d |\n",
 			   i, q->queued, q->head, q->tail);
 	}