net: hns3: remove two unused structures in hclge_cmd.h

struct hclge_mac_vlan_remove_cmd and hclge_mac_vlan_add_cmd are unused.
So removes them from hclge_cmd.h.

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>