wifi: mac80211: ibss: wait for in-flight TX on disconnect

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: ibss: wait for in-flight TX on disconnect While leaving an IBSS in ieee80211_ibss_disconnect() mac80211 flushes stations, turns the carrier off and immediately tells the driver to leave as well. While there may be synchronize_net() in station flush and in this code later, packets can still be transmitted due to cross-CPU race conditions after carrier off is set. Therefore, it's possible for a race to happen where a TX to the driver occurs while or after telling it to leave the IBSS. This can be confusing to drivers, and in the case of iwlwifi leads to an attempt to use invalid queues. Move netif_carrier_off() to occur before sta_info_flush() during IBSS disconnect, and add synchronize_net() if flushing didn't, so that the synchronize_net() always happens between turning the carrier off and telling the driver, avoiding this race.