usb: gadget: fsl_udc_core: should not call gadget driver's .unbind

It has already been covered by udc core

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/fsl_udc_core.c

@@ -1957,7 +1957,6 @@ static int fsl_udc_start(struct usb_gadget *g,
 						    &udc_controller->gadget);
 			if (retval < 0) {
 				ERR("can't bind to transceiver\n");
-				driver->unbind(&udc_controller->gadget);
 				udc_controller->driver = 0;
 				return retval;
 			}