net/hns3: get link state change through mailbox

net/hns3: get link state change through mailbox

Currently, firmware adds the function of sending message to PF driver
through mailbox when the link status is changed, hns3 PMD driver can
usually recognize link state change faster through the message.

And in some extreme cases, this way is not faster than existing method
regularly updating link status by issuing the command every second in PF
driver, because of the parallel processing of mailbox and command
messages in firmware. So we reserve updating link status using timers in
PF driver, and add querying link status by issuing command to the
firmware in '.link_update' ops implementation function named
hns3_dev_link_update to solve the out of date link status.

Signed-off-by: Hongbo Zheng <zhenghongbo3@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Huisong Li <lihuisong@huawei.com>