sched/fair: Generalize the detach_task interface

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8PIYZ
CVE: NA

Reference: https://lore.kernel.org/lkml/1541767840-93588-7-git-send-email-steven.sistare@oracle.com/



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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 Yu <serein.chengyu@huawei.com>