mac80211: fix enabling 4-address mode on a sta vif after assoc

mac80211: fix enabling 4-address mode on a sta vif after assoc

[ Upstream commit a5d3cbdb09ff1f52cbe040932e06c8b9915c6dad ]

Notify the driver about the 4-address mode change and also send a nulldata
packet to the AP to notify it about the change

Fixes: 1ff4e8f2dec8 ("mac80211: notify the driver when a sta uses 4-address mode")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210702050111.47546-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>