net: hns3: provide .get_cmdq_stat interface for the client

mainline inclusion
from mainline-v5.8-rc1
commit a4de0228
category: feature
bugzilla: NA
CVE: NA

----------------------------

This patch provides a new interface for the client to query
whether CMDQ is ready to work.

Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Reviewed-by: Yongxin Li <liyongxin1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>