driver core: bus: add irq_get_affinity callback to bus_type

Introducing a callback in struct bus_type so that a subsystem
can hook up the getters directly. This approach avoids exposing
random getters in any subsystems APIs.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Wagner <wagi@kernel.org>
Link: https://lore.kernel.org/r/20241202-refactor-blk-affinity-helpers-v6-1-27211e9c2cd5@kernel.org


Signed-off-by: Jens Axboe <axboe@kernel.dk>