thermal: of: Make thermal_zone_of_sensor_register return -ENODEV if a sensor OF node is missing

When devm_thermal_zone_of_sensor_register() is called from
hwmon_thermal_add_sensor() it is possible that the relevant sensor is
missing an OF node. In this case thermal_zone_of_sensor_register() returns
-EINVAL which causes hwmon_thermal_add_sensor() to fail as well. This patch
changes relevant return code of thermal_zone_of_sensor_register() to
-ENODEV, which is tolerated by hwmon_thermal_add_sensor().

Here is a particular case of such behaviour: the Marvell ethernet PHYs
driver registers hwmon device for the built-in temperature sensor (see
drivers/net/phy/marvell.c). Since the sensor doesn't have associated OF
node devm_hwmon_device_register() returns error which ultimately causes
failure of the PHY driver's probe function.
Signed-off-by: Peter Mamonov <pmamonov@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20190827143952.19591-1-pmamonov@gmail.com

drivers/thermal/of-thermal.c

@@ -493,7 +493,7 @@ thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
 
 	if (!dev || !dev->of_node) {
 		of_node_put(np);
-		return ERR_PTR(-EINVAL);
+		return ERR_PTR(-ENODEV);
 	}
 
 	sensor_np = of_node_get(dev->of_node);