usb: Remove redundant 'flush_workqueue()' calls

'destroy_workqueue()' already drains the queue before destroying it, so
there is no need to flush it explicitly.

Remove the redundant 'flush_workqueue()' calls.

This was generated with coccinelle:

@@
expression E;
@@
- flush_workqueue(E);
destroy_workqueue(E);

Acked-by: Shuah Khan <[e-mail]>
Acked-by: Peter Chen <[e-mail]> # for chipidea part
Signed-off-by: Christophe JAILLET <[e-mail]>
Link: https://lore.kernel.org/r/563123a811[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/chipidea/otg.c

···
  */
 void ci_hdrc_otg_destroy(struct ci_hdrc *ci)
 {
-	if (ci->wq) {
-		flush_workqueue(ci->wq);
+	if (ci->wq)
 		destroy_workqueue(ci->wq);
-	}
+
 	/* Disable all OTG irq and clear status */
 	hw_write_otgsc(ci, OTGSC_INT_EN_BITS | OTGSC_INT_STATUS_BITS,
 						OTGSC_INT_STATUS_BITS);

drivers/usb/gadget/udc/mv_udc_core.c

···
 
 	usb_del_gadget_udc(&udc->gadget);
 
-	if (udc->qwork) {
-		flush_workqueue(udc->qwork);
+	if (udc->qwork)
 		destroy_workqueue(udc->qwork);
-	}
 
 	/* free memory allocated in probe */
 	dma_pool_destroy(udc->dtd_pool);

drivers/usb/host/u132-hcd.c

···
 	platform_driver_unregister(&u132_platform_driver);
 	printk(KERN_INFO "u132-hcd driver deregistered\n");
 	wait_event(u132_hcd_wait, u132_instances == 0);
-	flush_workqueue(workqueue);
 	destroy_workqueue(workqueue);
 }
 

drivers/usb/phy/phy-mv-usb.c

···
 {
 	struct mv_otg *mvotg = platform_get_drvdata(pdev);
 
-	if (mvotg->qwork) {
-		flush_workqueue(mvotg->qwork);
+	if (mvotg->qwork)
 		destroy_workqueue(mvotg->qwork);
-	}
 
 	mv_otg_disable(mvotg);
 
···
 err_disable_clk:
 	mv_otg_disable_internal(mvotg);
 err_destroy_workqueue:
-	flush_workqueue(mvotg->qwork);
 	destroy_workqueue(mvotg->qwork);
 
 	return retval;

drivers/usb/usbip/usbip_event.c

···
 
 void usbip_finish_eh(void)
 {
-	flush_workqueue(usbip_queue);
 	destroy_workqueue(usbip_queue);
 	usbip_queue = NULL;
 }