fs: remove unused path_put_init()

This helper has been unused for a while now.

Link: https://lore.kernel.org/r/20240822-bewuchs-werktag-46672b3c0606@brauner


Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>