net: hns: add support for vlan TSO

The hip07 chip support vlan TSO, this patch adds NETIF_F_TSO
and NETIF_F_TSO6 flags to vlan_features to improve the
performance after adding vlan to the net ports.

Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>