net: hns: optimizate irq proccess for HNS V2

In hns V1, common_poll should check and clean fbd pkts, because it
can not pend irq to clean them if there is no new pkt comes in.
But hns V2 hw fixes this bug, and will pend irq itself to do this.
So, for hns V2, we set ring_data->fini_process to NULL.

Signed-off-by: Sheng Li <lisheng011@huawei.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>