smsc9420: SMSC LAN9420 10/100 PCI ethernet adapter

This patch adds a driver for the LAN9240 PCI ethernet adapter.

Changes since initial submission:
 - debug msg_level has been changed to use standard definitions
 - convert to use net_device_ops

Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>