!8327 wifi: mac80211: don't return unset power in ieee80211_get_tx_power()

Merge Pull Request from: @ci-robot 
 
PR sync from: Zheng Yejian <zhengyejian1@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/DG6AKVWIIMXUP737WPAF5PVDEKTISYGO/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9RE6D 
 
Link:https://gitee.com/openeuler/kernel/pulls/8327

 

Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>