sched/fair: Remove superfluous lock section in do_sched_cfs_slack_timer()

mainline inclusion
from mainline-v5.11-rc1
commit cdb31047
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6DDGM
CVE: NA

Reference: https://github.com/torvalds/linux/commit/cdb310474dece99985e4cdd2b96b1324e39c1c9d



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

Since ab93a4bc ("sched/fair: Remove distribute_running fromCFS
bandwidth"), there is nothing to protect between
raw_spin_lock_irqsave/store() in do_sched_cfs_slack_timer().

Signed-off-by: Hui Su <sh_def@163.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Link: https://lkml.kernel.org/r/20201030144621.GA96974@rlk


Signed-off-by: zhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>
Reviewed-by: zhangwei <zhangwei123171@jd.com>