net: mdio: fix resource leak in mdiobus_register_device()

Fix a possible leak in mdiobus_register_device() when both a
reset-gpio and a reset-controller are present.
Clean up the already claimed reset-gpio, when the registration of
the reset-controller fails, so when an error code is returned, the
device retains its state before the registration attempt.

Link: https://lore.kernel.org/all/20251106144603.39053c81@kernel.org/
Fixes: 71dd6c0 ("net: phy: add support for reset-controller")
Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
Link: https://patch.msgid.link/4b419377f8dd7d2f63f919d0f74a336c734f8fff.1762584481.git.buday.csaba@prolan.hu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Buday Csaba

drivers/net/phy/mdio_bus.c

@@ -73,8 +73,11 @@ int mdiobus_register_device(struct mdio_device *mdiodev)
 			return err;
 
 		err = mdiobus_register_reset(mdiodev);
-		if (err)
+		if (err) {
+			gpiod_put(mdiodev->reset_gpio);
+			mdiodev->reset_gpio = NULL;
 			return err;
+		}
 
 		/* Assert the reset signal */
 		mdio_device_reset(mdiodev, 1);