sched/pelt: Relax the sync of runnable_sum with runnable_avg

mainline inclusion
from mainline-v5.17-rc2
commit 95246d1e
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I78WM8

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.4-rc3&id=95246d1ec80b8d19d882cd8eb7ad094e63b41bb8



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Similarly to util_avg and util_sum, don't sync runnable_sum with the low
bound of runnable_avg but only ensure that runnable_sum stays in the
correct range.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Link: https://lkml.kernel.org/r/20220111134659.24961-4-vincent.guittot@linaro.org


Signed-off-by: Guan Jing <guanjing6@huawei.com>