ixgbe: extend firmware version support

Extend FW version reporting by displaying information from the iSCSI
or OEM block in the EEPROM.

This will allow us to more accurately identify the FW.

Signed-off-by: Paul Greenwalt <paul.greenwalt@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>