block: introduce max_write_streams queue limit

block: introduce max_write_streams queue limit

Drivers with hardware that support write streams need a way to export how
many are available so applications can generically query this.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
[hch: renamed hints to streams, removed stacking]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-4-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>