net: dsa: Fix NULL checking in dsa_slave_set_eee()

[ Upstream commit 00670cb8a73b10b10d3c40f045c15411715e4465 ]

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: 1be52e97ed3e ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/dsa/slave.c

@@ -639,7 +639,7 @@ 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)
@@ -659,7 +659,7 @@ 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)