net: phy: Fix PHY unbind crash

The PHY library does not deal very well with bind and unbind events. The first
thing we would see is that we were not properly canceling the PHY state machine
workqueue, so we would be crashing while dereferencing phydev->drv since there
is no driver attached anymore.
Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy_device.c

@@ -1784,6 +1784,8 @@ static int phy_remove(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
 
+	cancel_delayed_work_sync(&phydev->state_queue);
+
 	mutex_lock(&phydev->lock);
 	phydev->state = PHY_DOWN;
 	mutex_unlock(&phydev->lock);