net/hns3: fix link status change from firmware

net/hns3: fix link status change from firmware

When the hardware link status changes, the firmware proactively
reports the link status change message, and then driver update
link status. This feature is lack of a switch to control in PF
driver. Otherwise, this feature does not take effect when the
kernel PF driver that supports the feature is not loaded.

Fixes: 109e4dd1bd7a ("net/hns3: get link state change through mailbox")
Cc: stable@dpdk.org
Signed-off-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>