ovl: change ovl_workdir_cleanup() to take dir lock as needed.

ovl: change ovl_workdir_cleanup() to take dir lock as needed.

Rather than calling ovl_workdir_cleanup() with the dir already locked,
change it to take the dir lock only when needed.

Also change ovl_workdir_cleanup() to take a dentry for the parent rather
than an inode.

Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-16-neil@brown.name
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>