ath9k: P2P_CLIENT, get/set NOA correctly

In case we get BSS_CHANGED_P2P_PS early, from
mac80211, we didn't set NOA timer correctly,
while p2p_ps_vif was NULL.

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>