ath9k: dynack: use authentication messages for 'late' ack

ath9k: dynack: use authentication messages for 'late' ack

In order to properly support dynack in ad-hoc mode running
wpa_supplicant, take into account authentication frames for
'late ack' detection. This patch has been tested on devices
mounted on offshore high-voltage stations connected through
~24Km link

Reported-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>