ACPI: thinkpad-acpi: do not arm fan watchdog if it would not work

Do not enable/rearm the fan control safety watchdog if we would not be able
to do anything to the fan anyway.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/misc/thinkpad_acpi.c

@@ -3197,6 +3197,9 @@ static void fan_watchdog_reset(void)
 {
 	static int fan_watchdog_active = 0;
 
+	if (fan_control_access_mode == TPACPI_FAN_WR_NONE)
+		return;
+
 	if (fan_watchdog_active)
 		cancel_delayed_work(&fan_watchdog_task);