RDMA/hns: Support to query firmware version

mainline inclusion
from mainline-v5.13
commit 847d19a4
category: bugfix
bugzilla: NA
CVE: NA

Implement the ops named get_dev_fw_str to support ib_get_device_fw_str().

Signed-off-by: Shunfeng Yang <yangshunfeng2@huawei.com>
Signed-off-by: Yangyang Li <liyangyang20@huawei.com>
Reviewed-by: chunzhi hu <huchunzhi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>