mdio_bus: Simplify reset handling and extend to non-DT systems

Convert mdiobus_register_reset() from open-coded DT-only optional reset
handling to reset_control_get_optional_exclusive().  This not only
simplifies the code, but also adds support for lookup-based resets on
non-DT systems.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/mdio_bus.c

@@ -59,17 +59,11 @@ static int mdiobus_register_gpiod(struct mdio_device *mdiodev)
 
 static int mdiobus_register_reset(struct mdio_device *mdiodev)
 {
-	struct reset_control *reset = NULL;
-
-	if (mdiodev->dev.of_node)
-		reset = of_reset_control_get_exclusive(mdiodev->dev.of_node,
-						       "phy");
-	if (IS_ERR(reset)) {
-		if (PTR_ERR(reset) == -ENOENT || PTR_ERR(reset) == -ENOTSUPP)
-			reset = NULL;
-		else
+	struct reset_control *reset;
+
+	reset = reset_control_get_optional_exclusive(&mdiodev->dev, "phy");
+	if (IS_ERR(reset))
 		return PTR_ERR(reset);
-	}
 
 	mdiodev->reset_ctrl = reset;