net: remove dev_txq_stats_fold()

After recent changes, (percpu stats on vlan/tunnels...), we dont need
anymore per struct netdev_queue tx_bytes/tx_packets/tx_dropped counters.

Only remaining users are ixgbe, sch_teql, gianfar & macvlan :

1) ixgbe can be converted to use existing tx_ring counters.

2) macvlan incremented txq->tx_dropped, it can use the
dev->stats.tx_dropped counter.

3) sch_teql : almost revert ab35cd4b8f42 (Use net_device internal stats)
    Now we have ndo_get_stats64(), use it, even for "unsigned long"
fields (No need to bring back a struct net_device_stats)

4) gianfar adds a stats structure per tx queue to hold
tx_bytes/tx_packets

This removes a lockdep warning (and possible lockup) in rndis gadget,
calling dev_get_stats() from hard IRQ context.

Ref: http://www.spinics.net/lists/netdev/msg149202.html

Reported-by: Neil Jones <neiljay@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Jarek Poplawski <jarkao2@gmail.com>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
CC: Sandeep Gopalpet <sandeep.kumar@freescale.com>
CC: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index 45c4b7b..f1d4b45 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -433,7 +433,6 @@
 static struct net_device_stats *gfar_get_stats(struct net_device *dev)
 {
 	struct gfar_private *priv = netdev_priv(dev);
-	struct netdev_queue *txq;
 	unsigned long rx_packets = 0, rx_bytes = 0, rx_dropped = 0;
 	unsigned long tx_packets = 0, tx_bytes = 0;
 	int i = 0;
@@ -449,9 +448,8 @@
 	dev->stats.rx_dropped = rx_dropped;
 
 	for (i = 0; i < priv->num_tx_queues; i++) {
-		txq = netdev_get_tx_queue(dev, i);
-		tx_bytes += txq->tx_bytes;
-		tx_packets += txq->tx_packets;
+		tx_bytes += priv->tx_queue[i]->stats.tx_bytes;
+		tx_packets += priv->tx_queue[i]->stats.tx_packets;
 	}
 
 	dev->stats.tx_bytes = tx_bytes;
@@ -2108,8 +2106,8 @@
 	}
 
 	/* Update transmit stats */
-	txq->tx_bytes += skb->len;
-	txq->tx_packets ++;
+	tx_queue->stats.tx_bytes += skb->len;
+	tx_queue->stats.tx_packets++;
 
 	txbdp = txbdp_start = tx_queue->cur_tx;
 	lstatus = txbdp->lstatus;