iwlwifi: mvm: delay GTK setting in FW in AP mode

iwlwifi: mvm: delay GTK setting in FW in AP mode

In AP (and IBSS) mode, we can only set GTKs to firmware after we have
sent down the multicast station, but this we can only do after we've
enabled beaconing, etc.

However, during rfkill exit, hostapd will configure the keys before
starting the AP, and cfg80211/mac80211 accept it happily.

On earlier devices, this didn't bother us as GTK TX wasn't really
handled in firmware, we just put the key material into the TX cmd
and thus it only mattered when we actually transmitted a frame.

On newer devices, however, the firmware needs to track all of this
and that doesn't work if we add the key before the (multicast) sta
it belongs to.

To fix this, keep a list of keys to add during AP enable, and call
the function there.

Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>