mac80211: minstrel_ht: remove unused n_supported variable

clang with W=1 reports
net/mac80211/rc80211_minstrel_ht.c:1711:6: error: variable
  'n_supported' set but not used [-Werror,-Wunused-but-set-variable]
        int n_supported = 0;
            ^
This variable is not used so remove it.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230325132610.1334820-1-trix@redhat.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rc80211_minstrel_ht.c

@@ -1708,7 +1708,6 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 	struct sta_info *sta_info;
 	bool ldpc, erp;
 	int use_vht;
-	int n_supported = 0;
 	int ack_dur;
 	int stbc;
 	int i;
@@ -1791,8 +1790,6 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 				continue;
 
 			mi->supported[i] = mcs->rx_mask[nss - 1];
-			if (mi->supported[i])
-				n_supported++;
 			continue;
 		}
 
@@ -1819,9 +1816,6 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 
 		mi->supported[i] = minstrel_get_valid_vht_rates(bw, nss,
 				vht_cap->vht_mcs.tx_mcs_map);
-
-		if (mi->supported[i])
-			n_supported++;
 	}
 
 	sta_info = container_of(sta, struct sta_info, sta);