usb: gadget: r8a66597-udc: use udc-core's reset notifier

Replace usb_gadget_driver's disconnect with udc-core's reset notifier at
bus reset handler.
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/udc/r8a66597-udc.c

@@ -1345,7 +1345,7 @@ static void irq_device_state(struct r8a66597 *r8a66597)
 	if (dvsq == DS_DFLT) {
 		/* bus reset */
 		spin_unlock(&r8a66597->lock);
-		r8a66597->driver->disconnect(&r8a66597->gadget);
+		usb_gadget_udc_reset(&r8a66597->gadget, r8a66597->driver);
 		spin_lock(&r8a66597->lock);
 		r8a66597_update_usb_speed(r8a66597);
 	}