net: hns3: refactor out hclgevf_set_rss_tuple()

To make it more readable and maintainable, split
hclgevf_set_rss_tuple() into two parts.

Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>