md: prevent adding disks with larger logical_block_size to active arrays

md: prevent adding disks with larger logical_block_size to active arrays

When adding a disk to a md array, avoid updating the array's
logical_block_size to match the new disk. This prevents accidental
partition table loss that renders the array unusable.

The later patch will introduce a way to configure the array's
logical_block_size.

The issue was introduced before Linux 2.6.12-rc2.

Link: https://lore.kernel.org/linux-raid/20250918115759.334067-2-linan666@huaweicloud.com/
Fixes: d2e45eace8 ("[PATCH] Fix raid "bio too big" failures")
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Yu Kuai <yukuai@fnnas.com>