This fixes WARN_ONs when using AP_VLANs after station removal. The flush
call passed AP_VLAN vif to driver, but because these vifs are virtual and
not registered with drivers, we need to translate to the correct AP vif
first.

Closes: https://github.com/openwrt/openwrt/issues/12420
Fixes: 0b75a1b1 ("wifi: mac80211: flush queues on STA removal")
Fixes: d00800a2 ("wifi: mac80211: add flush_sta method")
Tested-by: Konstantin Demin <rockdrilla@gmail.com>
Tested-by: Koen Vandeputte <koen.vandeputte@citymesh.com>
Signed-off-by: Oldřich Jedlička <oldium.pro@gmail.com>
Link: https://lore.kernel.org/r/20231104141333.3710-1-oldium.pro@gmail.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>