usb: gadget: storage: remove nofua file when unbinding

The dev_attr_nofua file was created during fsg_bind() but
was never removed.  Made it a bit more symmetrical and added
code to remove the file in fsg_unbind().
Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Acked-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/file_storage.c

@@ -3178,6 +3178,7 @@ static void /* __init_or_exit */ fsg_unbind(struct usb_gadget *gadget)
 	for (i = 0; i < fsg->nluns; ++i) {
 		curlun = &fsg->luns[i];
 		if (curlun->registered) {
+			device_remove_file(&curlun->dev, &dev_attr_nofua);
 			device_remove_file(&curlun->dev, &dev_attr_ro);
 			device_remove_file(&curlun->dev, &dev_attr_file);
 			fsg_lun_close(curlun);