Documentation/auxiliary_bus: Clarify match_name

Provide example code for how the match name is formed and where it is
supposed to be set.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20211202044305.4006853-3-ira.weiny@intel.com


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