md/raid10: set chunk_sectors limit

Same as done for raid0, set chunk_sectors limit to appropriately set the
atomic write size limit.

Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20250711105258.3135198-5-john.g.garry@oracle.com


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