igc: Remove temporary workaround

PHY_CONTROL register works as defined in the IEEE 802.3 specification
(IEEE 802.3-2008 22.2.4.1). Tidy up the temporary workaround.

User impact: PHY can now be powered down when the ethernet link is down.

Testing hints: ip link set down <device> (or just disconnect the
ethernet cable).

Oldest tested NVM version is: 1045:740.

Fixes: 5586838 ("igc: Add code for PHY support")
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Author: Sasha Neftin

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

@@ -130,11 +130,7 @@ void igc_power_down_phy_copper(struct igc_hw *hw)
 	/* The PHY will retain its settings across a power down/up cycle */
 	hw->phy.ops.read_reg(hw, PHY_CONTROL, &mii_reg);
 	mii_reg |= MII_CR_POWER_DOWN;
-
-	/* Temporary workaround - should be removed when PHY will implement
-	 * IEEE registers as properly
-	 */
-	/* hw->phy.ops.write_reg(hw, PHY_CONTROL, mii_reg);*/
+	hw->phy.ops.write_reg(hw, PHY_CONTROL, mii_reg);
 	usleep_range(1000, 2000);
 }