cfg80211: clear connect keys when freeing them

When freeing the connect keys, clear the memory to avoid
having the key material stick around in memory "forever".

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/util.c

@@ -797,7 +797,7 @@ void cfg80211_upload_connect_keys(struct wireless_dev *wdev)
 				netdev_err(dev, "failed to set mgtdef %d\n", i);
 	}
 
-	kfree(wdev->connect_keys);
+	kzfree(wdev->connect_keys);
 	wdev->connect_keys = NULL;
 }