blk-cgroup: pass a gendisk to blkcg_init_queue and blkcg_exit_queue

Pass the gendisk to blkcg_init_disk and blkcg_exit_disk as part of moving
the blk-cgroup infrastructure to be gendisk based.  Also remove the
rather pointless kerneldoc comments for these internal functions with a
single caller each.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-7-hch@lst.de


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