USB: usb peripheral controller driver oops avoidance

I'm having problem with oopses when rebooting, if I modprobe g_serial
and rmmod g_serial and do a reboot I get an oops in device_shutdown().
The reason seems to be that usb_gadget_unregister_driver() doesn't do
enough cleanup.  With this at91_udc patch I don't get the oops.
Signed-off-by: Patrik Sevallius <patrik.sevallius@enea.com>
[ Same bug was in other peripheral controller drivers; fixed ]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/amd5536udc.c

@@ -2038,6 +2038,7 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 	spin_unlock_irqrestore(&dev->lock, flags);
 
 	driver->unbind(&dev->gadget);
+	dev->gadget.dev.driver = NULL;
 	dev->driver = NULL;
 
 	/* set SD */

drivers/usb/gadget/at91_udc.c

@@ -1616,6 +1616,8 @@ int usb_gadget_unregister_driver (struct usb_gadget_driver *driver)
 	local_irq_enable();
 
 	driver->unbind(&udc->gadget);
+	udc->gadget.dev.driver = NULL;
+	udc->gadget.dev.driver_data = NULL;
 	udc->driver = NULL;
 
 	DBG("unbound from %s\n", driver->driver.name);

drivers/usb/gadget/goku_udc.c

@@ -1422,6 +1422,7 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 	spin_unlock_irqrestore(&dev->lock, flags);
 
 	driver->unbind(&dev->gadget);
+	dev->gadget.dev.driver = NULL;
 
 	DBG(dev, "unregistered driver '%s'\n", driver->driver.name);
 	return 0;

drivers/usb/gadget/lh7a40x_udc.c

@@ -474,6 +474,7 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 	spin_unlock_irqrestore(&dev->lock, flags);
 
 	driver->unbind(&dev->gadget);
+	dev->gadget.dev.driver = NULL;
 	device_del(&dev->gadget.dev);
 
 	udc_disable(dev);

drivers/usb/gadget/m66592-udc.c

@@ -1508,6 +1508,7 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 	m66592_bclr(m66592, M66592_VBSE | M66592_URST, M66592_INTENB0);
 
 	driver->unbind(&m66592->gadget);
+	m66592->gadget.dev.driver = NULL;
 
 	init_controller(m66592);
 	disable_controller(m66592);

drivers/usb/gadget/pxa2xx_udc.c

@@ -1345,6 +1345,7 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 	local_irq_enable();
 
 	driver->unbind(&dev->gadget);
+	dev->gadget.dev.driver = NULL;
 	dev->driver = NULL;
 
 	device_del (&dev->gadget.dev);