net: hns: fix return value of the function about rss

Both .get_rxfh and .set_rxfh are always return 0, it should return result
from hardware when getting or setting rss. And the rss function should
return the correct data type.

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>