sw64: refactor platform dependent codes

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5XTK7



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This commit includes changes as follows:

- Refactor machine power interface functions similarly to other
  architectures.
- Keep legacy suspend implementation which may be deprecated some day.

Signed-off-by: Dai Xin <daixin@wxiat.com>
Reviewed-by: He Sheng <hesheng@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>