usb: dwc2: gadget: fix gadget unregistration in udc_stop() function

udc_stop() should clear ->driver pointer unconditionally to let the UDC
framework to work correctly with both registering/unregistering gadgets
and enabling/disabling gadgets by writing to
/sys/class/udc/*hsotg/soft_connect interface.
Acked-by: NPaul Zimmerman <paulz@synopsys.com>
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/dwc2/gadget.c

@@ -2937,9 +2937,7 @@ static int s3c_hsotg_udc_stop(struct usb_gadget *gadget,
 
 	spin_lock_irqsave(&hsotg->lock, flags);
 
-	if (!driver)
-		hsotg->driver = NULL;
-
+	hsotg->driver = NULL;
 	hsotg->gadget.speed = USB_SPEED_UNKNOWN;
 
 	spin_unlock_irqrestore(&hsotg->lock, flags);