net: hns3: make HW GRO handling compliant with SW GRO

Currently when a GRO packet is assembled by HW, the checksum is
modified to reflect the entire packet by HW and skb->ip_summed is
set to CHECKSUM_UNNECESSARY, which is not compliant with SW GRO.

This patch sets up skb's network and transport header, sets the
GRO packet's checksum according to pseudo header and set the
skb->ip_summed to CHECKSUM_PARTIAL.

This patch also use gso_size to distinguish GRO packet from
normal packet, use eth_type_vlan to check the VLAN type and set
the SKB_GSO_TCP_FIXEDID according to BD info during HW GRO info
processing.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>