net: hns: add dsaf misc operation method

The misc operation for different hw platform may be different, if using
current implementation, it will add a new branch on each function for
every new hw platform, so we add a method for this operation.

Signed-off-by: Kejian Yan <yankejian@huawei.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>