!841 【openEuler-1.0-LTS】cpufreq: conservative: Add a switch to enable fast mode

Merge Pull Request from: @xuesinian 
 
Frequency scaling strategy switch for fast mode. Enable conservative governor changing frequency a little bit quickly.

Conservative governor belongs to a slow frequency governor. In some scenarios where performance loss is significant. Therefore, endow the conservative governor with fast frequency scaling capability and add switches to use fast mode in these scenarios to reduce performance loss.

Related issue : #I78PCH 
 
Link:https://gitee.com/openeuler/kernel/pulls/841

 

Reviewed-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>