igc: Remove serdes comments from a description of methods

Serdes interface is not applicable for i225 devices.
Remove this from comments and make comments more clearly.
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>

drivers/net/ethernet/intel/igc/igc_main.c

@@ -115,7 +115,7 @@ void igc_reset(struct igc_adapter *adapter)
 }
 
 /**
- * igc_power_up_link - Power up the phy/serdes link
+ * igc_power_up_link - Power up the phy link
  * @adapter: address of board private structure
  */
 static void igc_power_up_link(struct igc_adapter *adapter)
@@ -129,7 +129,7 @@ static void igc_power_up_link(struct igc_adapter *adapter)
 }
 
 /**
- * igc_power_down_link - Power down the phy/serdes link
+ * igc_power_down_link - Power down the phy link
  * @adapter: address of board private structure
  */
 static void igc_power_down_link(struct igc_adapter *adapter)