sw64: add dynamic frequency scaling support

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56QDM



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Dynamic voltage and frequency scaling (DVFS) is a well-known technique
to reduce power/or energy consumption of various applications. But in
the past, cpu frequency scaling has to be done manually on sw64. Now we
add dynamic frequency scaling support, which allows system to scale
frequency dynamically according to workload.

Signed-off-by: Tang Jinyang <tangjinyang@wxiat.com>

Signed-off-by: Gu Zitao <guzitao@wxiat.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>