Revert "md/raid10: fix softlockup in raid10_unplug"

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I8UKFJ


CVE: NA

--------------------------------

This reverts commit 7efc0915.

The problem can be solved by commit 01044462 ("md/raid10: prevent soft
lockup while flush writes") from mainline, so revert this patch and apply
the mainline one.

Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>