smart_grid: introduce smart_grid_strategy_ctrl sysctl

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I7ZBSR


CVE: NA

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Considering for inheritance of the pre-verion code.

We make all task to the highest qos_level (grid_qos_level = 0),when
smart_grid strategy was disabled.

Otherwise, When smart_grid strategy was enabled, we use the task's
actually grid_qos_level.

Default smart_grid strategy was disable (=0).

Signed-off-by: Yipeng Zou <zouyipeng@huawei.com>