usb: gadget: gadgetfs: potential use after free in unbind()

ffs_data_put() can sometimes free "ffs" so I have moved the call down
a line below the dereference.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/f_fs.c

@@ -1417,8 +1417,8 @@ static void functionfs_unbind(struct ffs_data *ffs)
 		usb_ep_free_request(ffs->gadget->ep0, ffs->ep0req);
 		ffs->ep0req = NULL;
 		ffs->gadget = NULL;
-		ffs_data_put(ffs);
 		clear_bit(FFS_FL_BOUND, &ffs->flags);
+		ffs_data_put(ffs);
 	}
 }