md: use interruptible apis in idle/frozen_sync_thread

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6T6VY


CVE: NA

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Before refactoring idle and frozen from action_store, interruptible apis
is used so that hungtask warning won't be triggered if it takes too long
to finish indle/frozen sync_thread. This patch do the same.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>