driver core: bus: constify class_unregister/destroy()

The class_unregister() and class_destroy() function should be taking a
const * to struct class, not just a *, so fix that up.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230325084526.3622123-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>