net: hisilicon fix a bug on Hisilicon Network Subsystem

This patch fixes the wrong judgement of mac_id when get port num.

Signed-off-by: huangdaode <huangdaode@hisilicon.com>
Signed-off-by: yankejian <yankejian@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>