sched: Add switch for update_blocked_averages

hulk inclusion
category: feature
bugzilla: 175551 https://gitee.com/openeuler/kernel/issues/I4DVI3



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Avaliable for switch on/off for update_blocked_averages, it helps reducing
cpu usage when system in heavy load.

Signed-off-by: Yu Jiahua <yujiahua1@huawei.com>
Reviewed-by: Chen Hui <judy.chenhui@huawei.com>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>