net: phy: fix phy_disable_eee

genphy_c45_write_eee_adv() becomes a no-op if phydev->supported_eee
is cleared. That's not what we want because this function is still
needed to clear the EEE advertisement register(s).
Fill phydev->eee_broken_modes instead to ensure that userspace
can't re-enable EEE advertising.

Fixes: b55498f ("net: phy: add phy_disable_eee")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/57e2ae5f-4319-413c-b5c4-ebc8d049bc23@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: hkallweit

drivers/net/phy/phy_device.c

@@ -3012,10 +3012,11 @@ EXPORT_SYMBOL(phy_support_eee);
  */
 void phy_disable_eee(struct phy_device *phydev)
 {
-	linkmode_zero(phydev->supported_eee);
 	linkmode_zero(phydev->advertising_eee);
 	phydev->eee_cfg.tx_lpi_enabled = false;
 	phydev->eee_cfg.eee_enabled = false;
+	/* don't let userspace re-enable EEE advertisement */
+	linkmode_fill(phydev->eee_broken_modes);
 }
 EXPORT_SYMBOL_GPL(phy_disable_eee);