net: hns3: remove unused code in hns3_self_test()

NETIF_F_HW_VLAN_CTAG_FILTER is not set in netdev->hw_feature,
but set in netdev->features.

So the handler of NETIF_F_HW_VLAN_CTAG_FILTER in hns3_self_test() is
always true, remove it.

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