bpf: sched: Add helper functions to get cpu statistics

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5KUFB


CVE: NA

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Add the helper functions to get cpu statistics, as follows:
1.acquire cfs/rt/irq cpu load statitic.
2.acquire multiple types of nr_running statitic.
3.acquire cpu idle statitic.
4.acquire cpu capacity.

Based on CPU statistics in different dimensions, specific scheduling
policies can be implemented in bpf program.

Signed-off-by: Chen Hui <judy.chenhui@huawei.com>
Signed-off-by: Hui Tang <tanghui20@huawei.com>
Signed-off-by: Ren Zhijie <renzhijie2@huawei.com>
Signed-off-by: Hui Tang <tanghui20@huawei.com>