mac80211: remove some unused code

There are a number of unused variables that gcc
pointed out (when building with W=1) as well as
some conditions that can never be true due to
the datatypes used: unsigned values can't be
less than zero. Remove this code.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index ab39c4f..469d864 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2617,14 +2617,9 @@
 
 
 	if (elems.ht_cap_elem && elems.ht_operation && elems.wmm_param &&
-	    !(ifmgd->flags & IEEE80211_STA_DISABLE_11N)) {
-		struct ieee80211_supported_band *sband;
-
-		sband = local->hw.wiphy->bands[chan->band];
-
+	    !(ifmgd->flags & IEEE80211_STA_DISABLE_11N))
 		changed |= ieee80211_config_ht_tx(sdata, elems.ht_operation,
 						  bssid, true);
-	}
 
 	if (elems.country_elem && elems.pwr_constr_elem &&
 	    mgmt->u.probe_resp.capab_info &