md/raid5: use new apis to suspend array

Convert to use new apis, the old apis will be removed eventually.

These are not hot path, so performance is not concerned.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-10-yukuai1@huaweicloud.com