net: phy: smsc: bail out in lan87xx_read_status if genphy_read_status fails

If genphy_read_status fails then further access to the PHY may result
in unpredictable behavior. To prevent this bail out immediately if
genphy_read_status fails.

Fixes: 4223dbf ("net: phy: smsc: Re-enable EDPD mode for LAN87xx")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/026aa4f2-36f5-1c10-ab9f-cdb17dda6ac4@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: hkallweit

drivers/net/phy/smsc.c

@@ -199,8 +199,11 @@ static int lan95xx_config_aneg_ext(struct phy_device *phydev)
 static int lan87xx_read_status(struct phy_device *phydev)
 {
 	struct smsc_phy_priv *priv = phydev->priv;
+	int err;
 
-	int err = genphy_read_status(phydev);
+	err = genphy_read_status(phydev);
+	if (err)
+		return err;
 
 	if (!phydev->link && priv->energy_enable && phydev->irq == PHY_POLL) {
 		/* Disable EDPD to wake up PHY */