block: check for max_hw_sectors underflow

The logical block size need to be smaller than the max_hw_sector
setting, otherwise we can't even transfer a single LBA.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>