net: dsa: Fix NULL checking in dsa_slave_set_eee()

This function can't succeed if dp->pl is NULL.  It will Oops inside the
call to return phylink_ethtool_get_eee(dp->pl, e);

Fixes: 1be52e97 ("dsa: slave: eee: Allow ports to use phylink")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/slave.c

@@ -642,7 +642,7 @@ static int dsa_slave_set_eee(struct net_device *dev, struct ethtool_eee *e)
 	int ret;
 
 	/* Port's PHY and MAC both need to be EEE capable */
-	if (!dev->phydev && !dp->pl)
+	if (!dev->phydev || !dp->pl)
 		return -ENODEV;
 
 	if (!ds->ops->set_mac_eee)
@@ -662,7 +662,7 @@ static int dsa_slave_get_eee(struct net_device *dev, struct ethtool_eee *e)
 	int ret;
 
 	/* Port's PHY and MAC both need to be EEE capable */
-	if (!dev->phydev && !dp->pl)
+	if (!dev->phydev || !dp->pl)
 		return -ENODEV;
 
 	if (!ds->ops->get_mac_eee)