yama: document function parameter

Document the unused function parameter of yama_relation_cleanup() to
please kernel doc warnings.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240315125418.273104-2-cgzones@googlemail.com


Signed-off-by: Kees Cook <kees@kernel.org>