thinkpad_acpi: don't use [delayed_]work_pending()

There's no need to test whether a (delayed) work item in pending
before queueing, flushing or cancelling it.  Most uses are unnecessary
and quite a few of them are buggy.

Remove unnecessary pending tests from thinkpad_acpi.  Only compile
tested.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: ibm-acpi-devel@lists.sourceforge.net
Cc: platform-driver-x86@vger.kernel.org

drivers/platform/x86/thinkpad_acpi.c

@@ -4877,8 +4877,7 @@ static int __init light_init(struct ibm_init_struct *iibm)
 static void light_exit(void)
 {
 	led_classdev_unregister(&tpacpi_led_thinklight.led_classdev);
-	if (work_pending(&tpacpi_led_thinklight.work))
-		flush_workqueue(tpacpi_wq);
+	flush_workqueue(tpacpi_wq);
 }
 
 static int light_read(struct seq_file *m)