net: hns3: add hns3_gro_complete for HW GRO process

When a GRO packet is received by driver, the cwr field in the
struct tcphdr needs to be checked to decide whether to set the
SKB_GSO_TCP_ECN for skb_shinfo(skb)->gso_type.

So this patch adds hns3_gro_complete to do that, and adds the
hns3_handle_bdinfo to handle the hns3_gro_complete and
hns3_rx_checksum.

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