block: pass a request_queue to __blk_alloc_disk

Pass in a request_queue and assign disk->queue in __blk_alloc_disk to
ensure struct gendisk always has a valid ->queue pointer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816131910.615153-8-hch@lst.de


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