pkt_sched: Add qdisc_reset_all_tx().

Isolate callers that want to simply reset all the TX qdiscs from the
details of TX queues.

Use this in the ISDN code.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/i4l/isdn_net.c b/drivers/isdn/i4l/isdn_net.c
index 457bbd1..bb904a0 100644
--- a/drivers/isdn/i4l/isdn_net.c
+++ b/drivers/isdn/i4l/isdn_net.c
@@ -287,7 +287,7 @@
 		   BEWARE! This chunk of code cannot be called from hardware
 		   interrupt handler. I hope it is true. --ANK
 		 */
-		qdisc_reset(lp->netdev->dev->tx_queue.qdisc);
+		qdisc_reset_all_tx(lp->netdev->dev);
 	}
 	lp->dialstate = 0;
 	dev->rx_netdev[isdn_dc2minor(lp->isdn_device, lp->isdn_channel)] = NULL;