net/hns3: fix VF link status

net/hns3: fix VF link status

Currently, port link status is "up" in VF driver after user calling the
rte_eth_dev_stop API. This is unreasonable.

Therefore, this patch adjusts the strategy of getting link status from
PF driver for VF. VF driver should stop getting link status from PF by
canceling the alarm that VF driver send mailbox message to PF driver,
when the rte_eth_dev_stop API is called. And VF driver should restore
the alarm when the rte_eth_dev_start API is called.

Fixes: a5475d61fa34 ("net/hns3: support VF")
Cc: stable@dpdk.org
Signed-off-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>