netdevice ppp: Convert directly reference of netdev->priv

1. Use netdev_priv(dev) to replace dev->priv.
2. Alloc netdev's private data by alloc_netdev().

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed