qtnfmac: drop error reports for out-of-bounds key indexes

On disconnect wireless core attempts to remove all the supported keys.
Following cfg80211_ops conventions, firmware returns -ENOENT code
for the out-of-bound key indexes. This is a normal behavior,
so no need to report errors for this case.
Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/quantenna/qtnfmac/cfg80211.c

@@ -523,9 +523,16 @@ static int qtnf_del_key(struct wiphy *wiphy, struct net_device *dev,
 	int ret;
 
 	ret = qtnf_cmd_send_del_key(vif, key_index, pairwise, mac_addr);
-	if (ret)
-		pr_err("VIF%u.%u: failed to delete key: idx=%u pw=%u\n",
-		       vif->mac->macid, vif->vifid, key_index, pairwise);
+	if (ret) {
+		if (ret == -ENOENT) {
+			pr_debug("VIF%u.%u: key index %d out of bounds\n",
+				 vif->mac->macid, vif->vifid, key_index);
+		} else {
+			pr_err("VIF%u.%u: failed to delete key: idx=%u pw=%u\n",
+			       vif->mac->macid, vif->vifid,
+			       key_index, pairwise);
+		}
+	}
 
 	return ret;
 }