Documentation/auxiliary_bus: Add example code for module_auxiliary_driver()

Add an example code snipit to the module_auxiliary_driver()
documentation which is consistent with the other example code in the
elsewhere in the documentation.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20211202044305.4006853-6-ira.weiny@intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>