usb: gadget: at91_udc: 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 at91_udc.  Only compile tested.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: linux-usb@vger.kernel.org
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/at91_udc.c

@@ -1621,7 +1621,6 @@ static void at91_vbus_timer(unsigned long data)
 	 * bus such as i2c or spi which may sleep, so schedule some work
 	 * to read the vbus gpio
 	 */
-	if (!work_pending(&udc->vbus_timer_work))
 	schedule_work(&udc->vbus_timer_work);
 }