thermal: db8500: Fix checking return value of thermal_zone_device_register

thermal_zone_device_register() returns ERR_PTR on error, thus use
IS_ERR rather than IS_ERR_OR_NULL to check return value.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/db8500_thermal.c

@@ -447,7 +447,7 @@ static int db8500_thermal_probe(struct platform_device *pdev)
 	pzone->therm_dev = thermal_zone_device_register("db8500_thermal_zone",
 		ptrips->num_trips, 0, pzone, &thdev_ops, NULL, 0, 0);
 
-	if (IS_ERR_OR_NULL(pzone->therm_dev)) {
+	if (IS_ERR(pzone->therm_dev)) {
 		dev_err(&pdev->dev, "Register thermal zone device failed.\n");
 		return PTR_ERR(pzone->therm_dev);
 	}