igb: Fix get_fw_version function for all parts

This patch fixes issues found with older parts and older NVM tools in the
display of the version in ethtool.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
4 files changed