ath9k: setup rxfilter when offchannel

Setup rxfiler correctly for offchannel ctx.

This fix problem we didn't configure rxfilter, next
didn't receive probe requests and next failed
p2p_find. This was seen when ath9k loaded with
use_chanctx=1

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

drivers/net/wireless/ath/ath9k/main.c

@@ -1468,6 +1468,9 @@ static void ath9k_configure_filter(struct ieee80211_hw *hw,
 	spin_lock_bh(&sc->chan_lock);
 	ath_for_each_chanctx(sc, ctx)
 		ctx->rxfilter = *total_flags;
+#ifdef CONFIG_ATH9K_CHANNEL_CONTEXT
+	sc->offchannel.chan.rxfilter = *total_flags;
+#endif
 	spin_unlock_bh(&sc->chan_lock);
 
 	ath9k_ps_wakeup(sc);