igc: Remove symbol error counter

Accordance to the i225 datasheet symbol error counter does not
applicable to the i225 device.
This patch comes to clean up this counter.

Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>