usb: gadget: udc-core: call ->disconnect() when soft disconnecting

when disconnecting from host using our soft_connect
sysfs interface, also let the gadget driver know about
it by calling the gadget driver's ->disconnect()
method.

No problems have been found while not calling ->disconnect()
so far, it's just good convention.
Signed-off-by: Felipe Balbi <balbi@ti.com>

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

@@ -517,6 +517,7 @@ static ssize_t usb_udc_softconn_store(struct device *dev,
 		usb_gadget_connect(udc->gadget);
 	} else if (sysfs_streq(buf, "disconnect")) {
 		usb_gadget_disconnect(udc->gadget);
+		udc->driver->disconnect(udc->gadget);
 		usb_gadget_udc_stop(udc->gadget, udc->driver);
 	} else {
 		dev_err(dev, "unsupported command '%s'\n", buf);