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>
diff --git a/drivers/usb/gadget/net2272.c b/drivers/usb/gadget/net2272.c
index ca15405..059cfe5 100644
--- a/drivers/usb/gadget/net2272.c
+++ b/drivers/usb/gadget/net2272.c
@@ -1453,7 +1453,7 @@
 	struct net2272 *dev;
 	unsigned i;
 
-	if (!driver || !driver->unbind || !driver->setup ||
+	if (!driver || !driver->setup ||
 	    driver->max_speed != USB_SPEED_HIGH)
 		return -EINVAL;