net: hns3: add suspend/resume function for hns3 driver

driver inclusion
category: feature
bugzilla: NA
CVE: NA

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The suspend and resume feature is useful when you want to
save the current state of your machine, and continue work
later from the same state. This patch makes the hns3 net
device work form the same state after s3 and s4.

Signed-off-by: Weiwei Deng <dengweiwei@huawei.com>
Signed-off-by: Hao Shen <shenhao21@huawei.com>
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Reviewed-by: Zhong Zhaohui <zhongzhaohui@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>