[netdrvr] via-velocity: misc. cleanups

- const-ify pci_device_id table
- clean up pci_device_id table with PCI_DEVICE()
- don't store internal pointer in pci_device_id table,
  use pci_device_id::driver_data as an integer index
- use dev_printk() for messages where eth%d prefix is unavailable
- formatting fixes

Signed-off-by: Jeff Garzik <jeff@garzik.org>