ath9k: fix a regression in PS frame filter handling

Only leave filtering enabled for AP or VLAN interfaces, clear the
destination mask for all other interfaces.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Reported-by: Ben Greear <greearb@candelatech.com>
Tested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 9dd72d8..3381609 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -1782,6 +1782,11 @@
 	struct ieee80211_key_conf ps_key = { };
 
 	ath_node_attach(sc, sta);
+
+	if (vif->type != NL80211_IFTYPE_AP &&
+	    vif->type != NL80211_IFTYPE_AP_VLAN)
+		return 0;
+
 	an->ps_key = ath_key_config(common, vif, sta, &ps_key);
 
 	return 0;