wifi: mac80211: fix TXQ error path and cleanup

We currently call ieee80211_txq_teardown_flows() as part
of ieee80211_remove_interfaces(), but that's not really
right in case of HW registration failures, specifically
rate control. Call it separately to fix that issue.

Reported-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>