sched/fair: Generalize the detach_task interface

hulk inclusion
category: feature
bugzilla: 38261, https://bugzilla.openeuler.org/show_bug.cgi?id=23


CVE: NA

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

The detach_task function takes a struct lb_env argument, but only needs a
few of its members.  Pass the rq and cpu arguments explicitly so the
function may be called from code that is not based on lb_env.  No
functional change.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>