mac80211: minstrel_ht: fix MCS_GROUP_RATES usage

Commit 5935839ad735 ("mac80211: improve minstrel_ht rate sorting by
throughput & probability") replaced the constant 8 with MCS_GROUP_RATES
when getting the number of streams of an HT MCS. See commit 7a5e3fa2c81c
("mac80211: minstrel_ht: replace some occurences of MCS_GROUP_RATES").

Fixes: 5935839ad735 ("mac80211: improve minstrel_ht rate sorting by throughput & probability")
Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rc80211_minstrel_ht.c

@@ -135,7 +135,7 @@ minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
 static int
 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
 {
-	return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
+	return GROUP_IDX((rate->idx / 8) + 1,
 			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
 			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
 }