block: decouple blk_set_stacking_limits from blk_set_default_limits

blk_set_stacking_limits uses very little from blk_set_default_limits.
Open code these initializations in preparation for rewriting
blk_set_default_limits.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240213073425.1621680-4-hch@lst.de


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