driver core: bus: bus iterator cleanups

Convert the bus_for_each_dev(), bus_find_device, and bus_for_each_drv()
functions to use bus_to_subsys() and not use the back-pointer to the
private structure.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230208111330.439504-13-gregkh@linuxfoundation.org


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