of_mdio: add helper to deregister fixed-link PHYs

Add helper to deregister fixed-link PHYs registered using
of_phy_register_fixed_link().

Convert the two drivers that care to deregister their fixed-link PHYs to
use the new helper, but note that most drivers currently fail to do so.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/of/of_mdio.c

@@ -490,3 +490,18 @@ int of_phy_register_fixed_link(struct device_node *np)
 	return -ENODEV;
 }
 EXPORT_SYMBOL(of_phy_register_fixed_link);
+
+void of_phy_deregister_fixed_link(struct device_node *np)
+{
+	struct phy_device *phydev;
+
+	phydev = of_phy_find_device(np);
+	if (!phydev)
+		return;
+
+	fixed_phy_unregister(phydev);
+
+	put_device(&phydev->mdio.dev);	/* of_phy_find_device() */
+	phy_device_free(phydev);	/* fixed_phy_register() */
+}
+EXPORT_SYMBOL(of_phy_deregister_fixed_link);