thermal: Fix test of unsigned in thermal_cooling_device_cur_state_store()

state is unsigned long so the test did not work.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/thermal/thermal_sys.c

@@ -374,7 +374,7 @@ thermal_cooling_device_cur_state_store(struct device *dev,
 	if (!sscanf(buf, "%ld\n", &state))
 		return -EINVAL;
 
-	if (state < 0)
+	if ((long)state < 0)
 		return -EINVAL;
 
 	result = cdev->ops->set_cur_state(cdev, state);