mac80211: minstrel_ht: fix where rate stats are stored (fixes debugfs output)

Using an ath9k card the debugfs output of minstrel_ht looks like the following
(note the zero values for the first four rates sum-of success/attempts):

             best    ____________rate__________    ____statistics___    _____last____    ______sum-of________
mode guard #  rate   [name   idx airtime  max_tp]  [avg(tp) avg(prob)]  [retry|suc|att]  [#success | #attempts]
OFDM       1    DP     6.0M  272    1640     5.2       3.1      53.8       3     0 0             0   0
OFDM       1   C       9.0M  273    1104     7.7       4.6      53.8       4     0 0             0   0
OFDM       1  B       12.0M  274     836    10.0       6.0      53.8       4     0 0             0   0
OFDM       1 A    S   18.0M  275     568    14.3       8.5      53.8       5     0 0             0   0
OFDM       1      S   24.0M  276     436    18.1       0.0       0.0       5     0 1            80   1778
OFDM       1          36.0M  277     300    24.9       0.0       0.0       0     0 1             0   107
OFDM       1      S   48.0M  278     236    30.4       0.0       0.0       0     0 0             0   75
OFDM       1          54.0M  279     212    33.0       0.0       0.0       0     0 0             0   72

Total packet count::    ideal 16582      lookaround 885
Average # of aggregated frames per A-MPDU: 1.0

Debugging showed that the rate statistics for the first four rates where
stored in the MINSTREL_CCK_GROUP instead of the MINSTREL_OFDM_GROUP because
in minstrel_ht_get_stats() the supported check was not honoured as done in
various other places, e.g net/mac80211/rc80211_minstrel_ht_debugfs.c:

 74                 if (!(mi->supported[i] & BIT(j)))
 75                         continue;

With the patch applied the output looks good:

              best    ____________rate__________    ____statistics___    _____last____    ______sum-of________
mode guard #  rate   [name   idx airtime  max_tp]  [avg(tp) avg(prob)]  [retry|suc|att]  [#success | #attempts]
OFDM       1    D      6.0M  272    1640     5.2       5.2     100.0       3     0 0             1   1
OFDM       1   C       9.0M  273    1104     7.7       7.7     100.0       4     0 0            38   38
OFDM       1  B       12.0M  274     836    10.0       9.9      89.5       4     2 2           372   395
OFDM       1 A   P    18.0M  275     568    14.3      14.3      97.2       5    52 53         6956   7181
OFDM       1      S   24.0M  276     436    18.1       0.0       0.0       0     0 1             6   163
OFDM       1          36.0M  277     300    24.9       0.0       0.0       0     0 1             0   35
OFDM       1      S   48.0M  278     236    30.4       0.0       0.0       0     0 0             0   38
OFDM       1      S   54.0M  279     212    33.0       0.0       0.0       0     0 0             0   38

Total packet count::    ideal 7097      lookaround 287
Average # of aggregated frames per A-MPDU: 1.0
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Link: https://lore.kernel.org/r/20220404165414.1036-1-ps.report@gmx.netSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rc80211_minstrel_ht.c

@@ -362,6 +362,9 @@ minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 
 	group = MINSTREL_CCK_GROUP;
 	for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++) {
+		if (!(mi->supported[group] & BIT(idx)))
+			continue;
+
 		if (rate->idx != mp->cck_rates[idx])
 			continue;