usb: gadget: Refactor request completion

Use the recently introduced usb_gadget_giveback_request() in favor of
direct invocation of the completion routine.

All places in drivers/usb/ matching "[-.]complete(" were replaced with a
call to usb_gadget_giveback_request(). This was compile-tested with all
ARM drivers enabled and runtime-tested for musb.

Signed-off-by: Michal Sojka <sojka@merica.cz>
Acked-by: Felipe Balbi <balbi@ti.com>
Tested-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_gadget.c

@@ -176,7 +176,7 @@ __acquires(ep->musb->lock)
 				ep->end_point.name, request,
 				req->request.actual, req->request.length,
 				request->status);
-	req->request.complete(&req->ep->end_point, &req->request);
+	usb_gadget_giveback_request(&req->ep->end_point, &req->request);
 	spin_lock(&musb->lock);
 	ep->busy = busy;
 }