USB: net2280: Remove ->disconnect() callback from net2280_pullup()

The net2280 UDC driver invokes the gadget driver's ->disconnect()
callback routine when the net2280_pullup() routine turns off the D+
pullup.  This is now unnecessary, because the gadget core performs the
callback on our behalf.  This patch removes the unneeded callback.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/net2280.c

@@ -1550,9 +1550,6 @@ static int net2280_pullup(struct usb_gadget *_gadget, int is_on)
 
 	spin_unlock_irqrestore(&dev->lock, flags);
 
-	if (!is_on && dev->driver)
-		dev->driver->disconnect(&dev->gadget);
-
 	return 0;
 }