Revert "bdi: fix kabi for struct backing_dev_info"

hulk inclusion
category: bugfix
bugzilla: 30939
CVE: NA
---------------------------

The kabi can be broken before official release.

This reverts commit f8589079659b51222d86a1cb8fd9129752b0d97c.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-By: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>