net: phy: Handle not having GPIO enabled in the kernel

If CONFIG_GPIOLIB is disabled, fwnode_get_named_gpiod() becomes a stub
function, which return -ENOSYS. Handle this in the same way as
-ENOENT, i.e. assume there is no GPIO used to reset the PHYs.

Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Fixes: bafbdd527d ("phylib: Add device reset GPIO support")
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/mdio_bus.c

@@ -56,7 +56,8 @@ static int mdiobus_register_gpiod(struct mdio_device *mdiodev)
 		gpiod = fwnode_get_named_gpiod(&mdiodev->dev.of_node->fwnode,
 					       "reset-gpios", 0, GPIOD_OUT_LOW,
 					       "PHY reset");
-	if (PTR_ERR(gpiod) == -ENOENT)
+	if (PTR_ERR(gpiod) == -ENOENT ||
+	    PTR_ERR(gpiod) == -ENOSYS)
 		gpiod = NULL;
 	else if (IS_ERR(gpiod))
 		return PTR_ERR(gpiod);