net: hns3: MAC table entry count function increases operation 0 value protection measures

When updating the available MAC VLAN table counts,
MAC VLAN table entry count function adds
operation 0 value protection measures.

Signed-off-by: liuzhongzhu <liuzhongzhu@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>