block: Remove unused blk_limits_io_{min,opt}

blk_limits_io_min and blk_limits_io_opt are unused since the
recent commit
  0a94a469 ("dm: stop using blk_limits_io_{min,opt}")

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://lore.kernel.org/r/20240920004817.676216-1-linux@treblig.org


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