net: sparx5: unregister blocking notifier on init failure

In the Linux kernel, the following vulnerability has been resolved: net: sparx5: unregister blocking notifier on init failure sparx5_register_notifier_blocks() registers the switchdev blocking notifier before allocating the ordered workqueue. If the workqueue allocation fails, the error path unregisters the switchdev and netdevice notifiers, but leaves the blocking notifier registered. Add a separate error label for the workqueue allocation failure path and unregister the switchdev blocking notifier there.