mac80211: free peer keys before vif down in mesh

freeing peer keys after vif down is resulting in peer key uninstall
to fail due to interface lookup failure. so fix that.
Signed-off-by: Pradeep Kumar Chitrapu <pradeepc@codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mesh.c

@@ -929,6 +929,7 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
 
 	/* flush STAs and mpaths on this iface */
 	sta_info_flush(sdata);
+	ieee80211_free_keys(sdata, true);
 	mesh_path_flush_by_iface(sdata);
 
 	/* stop the beacon */