nl80211: Zero out the connection keys memory when freeing them.

The connection keys are zeroed out in all other cases except this
one. Let's fix the last one as well.
Signed-off-by: Ola Olsson <ola.olsson@sonymobile.com>
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -7547,7 +7547,7 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
 
 		if ((ibss.chandef.width != NL80211_CHAN_WIDTH_20_NOHT) &&
 		    no_ht) {
-			kfree(connkeys);
+			kzfree(connkeys);
 			return -EINVAL;
 		}
 	}