md: improve return types of badblocks handling functions

md: improve return types of badblocks handling functions

rdev_set_badblocks() only indicates success/failure, so convert its return
type from int to boolean for better semantic clarity.

rdev_clear_badblocks() return value is never used by any caller, convert it
to void. This removes unnecessary value returns.

Also update narrow_write_error() in both raid1 and raid10 to use boolean
return type to match rdev_set_badblocks().

Signed-off-by: Zheng Qixing <zhengqixing@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250227075507.151331-12-zhengqixing@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>