thermal/drivers/hwmon: Cleanup coding style a bit

Function thermal_add_hwmon_sysfs, hwmon will be NULL when
new_hwmon_device = 0, so there is no need to check, kfree will
handle NULL point.
Signed-off-by: Bernard Zhao <bernard@vivo.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201102023121.3312-1-bernard@vivo.com

drivers/thermal/thermal_hwmon.c

@@ -206,7 +206,6 @@ int thermal_add_hwmon_sysfs(struct thermal_zone_device *tz)
 	if (new_hwmon_device)
 		hwmon_device_unregister(hwmon->device);
  free_mem:
-	if (new_hwmon_device)
 	kfree(hwmon);
 
 	return result;