igc: Remove copper fiber switch control

i225 device support copper mode only
PHY signal detect indication for copper fiber switch
not applicable to i225 part

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>