net/hns3: fix processing link status message on PF

net/hns3: fix processing link status message on PF

The opcode of the link status notification message reported by the
firmware is zero, it will be filtered out because driver treats it as
already processed message. As a result, the PF can't update the link
status in a timely manner.

Because only VF can set opcode to zero when processing mailbox message,
we add a judgment to make sure the PF messages will not be filtered out.

Fixes: dbbbad23e380 ("net/hns3: fix VF handling LSC event in secondary process")
Cc: stable@dpdk.org
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Signed-off-by: Min Hu (Connor) <humin29@huawei.com>