badblocks: fix the using of MAX_BADBLOCKS

badblocks: fix the using of MAX_BADBLOCKS

The number of badblocks cannot exceed MAX_BADBLOCKS, but it should be
allowed to equal MAX_BADBLOCKS.

Fixes: aa511ff8218b ("badblocks: switch to the improved badblock handling code")
Fixes: c3c6a86e9efc ("badblocks: add helper routines for badblock ranges handling")
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Coly Li <colyli@kernel.org>
Link: https://lore.kernel.org/r/20250227075507.151331-7-zhengqixing@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>