net: hns3: fix vf link setting failed when no vf driver loaded

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I58AJW


CVE: NA

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When no vf driver loaded, setting vf link state will return
fail. This patch adds check for vf keep alive, if vf keep alive
not exist, then just return success.

Fixes: 475febd3 ("net: hns3: PF add support for pushing link status to VFs")

Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Reviewed-by: li yongxin <liyongxin1@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>