usb: chipidea: drop redundant NULL check

Currently, gadget can't be NULL in _gadget_stop_activity().
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reported-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/udc.c

@@ -583,9 +583,6 @@ static int _gadget_stop_activity(struct usb_gadget *gadget)
 	struct ci13xxx    *udc = container_of(gadget, struct ci13xxx, gadget);
 	unsigned long flags;
 
-	if (gadget == NULL)
-		return -EINVAL;
-
 	spin_lock_irqsave(&udc->lock, flags);
 	udc->gadget.speed = USB_SPEED_UNKNOWN;
 	udc->remote_wakeup = 0;