mac80211: check DSSS params IE length in parser

It's always just one byte, so check for that and
remove the length field from the parser struct.

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

net/mac80211/mesh.c

@@ -907,7 +907,7 @@ static void ieee80211_mesh_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
 	    (!elems.rsn && sdata->u.mesh.security != IEEE80211_MESH_SEC_NONE))
 		return;
 
-	if (elems.ds_params && elems.ds_params_len == 1)
+	if (elems.ds_params)
 		freq = ieee80211_channel_to_frequency(elems.ds_params[0], band);
 	else
 		freq = rx_status->freq;