share_pool: Introduce struct sp_spg_stat

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4EUVI


CVE: NA

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In multi-group mode, we introduce struct sp_spg_stat which represents
statistics for an sp_group. It is the accumulation of all structs of
spg_proc_stat in an sp_group.

Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>