Connecting to an AP with WPA2 security may fail. The IQK
and the EAPOL 4-way handshake may overlap because the
driver does IQK right after assoc success.

For 802.11n devices, the IQK is done in the driver and it
could require more than 100ms to complete. During IQK, any
TX/RX events are paused. So if the EAPOL 4-way handshake
started before IQK finished, then the 1/4 and 2/4 part of
the handshake could be dropped. The AP will then issue
deauth with reason IEEE8021X_FAILED (23).

To resolve this, move IQK routine into managed TX prepare
(ieee80211_ops::mgd_prepare_tx()). The callback is called
before the managed frames (auth/assoc) are sent. This will
make sure that the IQK is completed before the handshake
starts. But don't do IQK during scanning because doing it
on each channel will take too long.

For 802.11ac devices, the IQK is done in firmware and it
takes less time to complete. Therefore we don't see a
failure during the EAPOL 4-way handshake. But it is still
worth moving the IQK into ieee80211_ops::mgd_prepare_tx().

Fixes: f5df1a8b ("rtw88: 8723d: Add 8723DE to Kconfig and Makefile")
Tested-by: You-Sheng Yang <vicamo.yang@canonical.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200529025009.2468-4-yhchuang@realtek.com