netxen: cleanup unused variables/functions

o Reduce access to global arrays in data path.
o Remove duplicate/unused variables, unecessary alignment constraints.
o Use correct pci_dev instead of fallback device for consistent
  allocations.
o Disable ethtool set_eeprom functionality for now, it was only used
  for flashing firmware.

Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>