8390: add common net_device ops

Fix the defactoring of ei_XXX functions in 8390 and 8390p.
Remove the tx_timeout hack since no driver including the 3c503
overrides tx_timeout at this time, looks like a legacy thing.

Also, since several drivers all have same hooks, provide common
netdev_ops.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>