syncppp: Fix crashes.

The syncppp layer wants a mid-level netdev private pointer.

It was using netdev->priv but that only worked by accident,
and thus this scheme was broken when the device private
allocation strategy changed.

Add a proper mid-layer private pointer for uses like this,
update syncppp and all users, and remove the HDLC_PPP broken
tag from drivers/net/wan/Kconfig

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/wan/cosa.c b/drivers/net/wan/cosa.c
index 45ddfc9..b0fce13 100644
--- a/drivers/net/wan/cosa.c
+++ b/drivers/net/wan/cosa.c
@@ -629,7 +629,7 @@
 	d->base_addr = chan->cosa->datareg;
 	d->irq = chan->cosa->irq;
 	d->dma = chan->cosa->dma;
-	d->priv = chan;
+	d->ml_priv = chan;
 	sppp_attach(&chan->pppdev);
 	if (register_netdev(d)) {
 		printk(KERN_WARNING "%s: register_netdev failed.\n", d->name);
@@ -650,7 +650,7 @@
 
 static int cosa_sppp_open(struct net_device *d)
 {
-	struct channel_data *chan = d->priv;
+	struct channel_data *chan = d->ml_priv;
 	int err;
 	unsigned long flags;
 
@@ -690,7 +690,7 @@
 
 static int cosa_sppp_tx(struct sk_buff *skb, struct net_device *dev)
 {
-	struct channel_data *chan = dev->priv;
+	struct channel_data *chan = dev->ml_priv;
 
 	netif_stop_queue(dev);
 
@@ -701,7 +701,7 @@
 
 static void cosa_sppp_timeout(struct net_device *dev)
 {
-	struct channel_data *chan = dev->priv;
+	struct channel_data *chan = dev->ml_priv;
 
 	if (test_bit(RXBIT, &chan->cosa->rxtx)) {
 		chan->stats.rx_errors++;
@@ -720,7 +720,7 @@
 
 static int cosa_sppp_close(struct net_device *d)
 {
-	struct channel_data *chan = d->priv;
+	struct channel_data *chan = d->ml_priv;
 	unsigned long flags;
 
 	netif_stop_queue(d);
@@ -800,7 +800,7 @@
 
 static struct net_device_stats *cosa_net_stats(struct net_device *dev)
 {
-	struct channel_data *chan = dev->priv;
+	struct channel_data *chan = dev->ml_priv;
 	return &chan->stats;
 }
 
@@ -1217,7 +1217,7 @@
 	int cmd)
 {
 	int rv;
-	struct channel_data *chan = dev->priv;
+	struct channel_data *chan = dev->ml_priv;
 	rv = cosa_ioctl_common(chan->cosa, chan, cmd, (unsigned long)ifr->ifr_data);
 	if (rv == -ENOIOCTLCMD) {
 		return sppp_do_ioctl(dev, ifr, cmd);