block: remove unused queue limits API

Remove all APIs that are unused now that sd and sr have been converted
to the atomic queue limits API.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240531074837.1648501-14-hch@lst.de


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