igc: Remove unneeded check for copper media type

PHY of the i225 device support only copper mode.
There is no point to check media type in the
igc_power_up_link() method.

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>