usb: gadget: net2272: do not need to judge gadget driver's .unbind

It has already been covered by udc core, besides, we do not
need unbind at .udc_start
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/net2272.c

@@ -1453,7 +1453,7 @@ static int net2272_start(struct usb_gadget *_gadget,
 	struct net2272 *dev;
 	unsigned i;
 
-	if (!driver || !driver->unbind || !driver->setup ||
+	if (!driver || !driver->setup ||
 	    driver->max_speed != USB_SPEED_HIGH)
 		return -EINVAL;