net: hns3: rename a member in struct hclge_mac_ethertype_idx_rd_cmd

The member 'mac_add' defined in hclge_mac_ethertype_idx_rd_cmd
means MAC address, so 'mac_addr' is a better name for it.

Signed-off-by: Guojia Liao <liaoguojia@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>