mac80211: move station statistics into sub-structs

Group station statistics by where they're (mostly) updated
(TX, RX and TX-status) and group them into sub-structs of
the struct sta_info.

Also rename the variables since the grouping now makes it
obvious where they belong.

This makes it easier to identify where the statistics are
updated in the code, and thus easier to think about them.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index bd853e7..2001555 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -647,7 +647,7 @@
 		return NULL;
 	}
 
-	sta->last_rx = jiffies;
+	sta->rx_stats.last_rx = jiffies;
 
 	/* make sure mandatory rates are always added */
 	sband = local->hw.wiphy->bands[band];
@@ -669,7 +669,8 @@
 
 	list_for_each_entry_rcu(sta, &local->sta_list, list) {
 		if (sta->sdata == sdata &&
-		    time_after(sta->last_rx + IEEE80211_IBSS_MERGE_INTERVAL,
+		    time_after(sta->rx_stats.last_rx +
+			       IEEE80211_IBSS_MERGE_INTERVAL,
 			       jiffies)) {
 			active++;
 			break;
@@ -1235,7 +1236,7 @@
 	if (!sta)
 		return;
 
-	sta->last_rx = jiffies;
+	sta->rx_stats.last_rx = jiffies;
 
 	/* make sure mandatory rates are always added */
 	sband = local->hw.wiphy->bands[band];
@@ -1253,7 +1254,7 @@
 	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta, *tmp;
 	unsigned long exp_time = IEEE80211_IBSS_INACTIVITY_LIMIT;
-	unsigned long exp_rsn_time = IEEE80211_IBSS_RSN_INACTIVITY_LIMIT;
+	unsigned long exp_rsn = IEEE80211_IBSS_RSN_INACTIVITY_LIMIT;
 
 	mutex_lock(&local->sta_mtx);
 
@@ -1261,8 +1262,8 @@
 		if (sdata != sta->sdata)
 			continue;
 
-		if (time_after(jiffies, sta->last_rx + exp_time) ||
-		    (time_after(jiffies, sta->last_rx + exp_rsn_time) &&
+		if (time_after(jiffies, sta->rx_stats.last_rx + exp_time) ||
+		    (time_after(jiffies, sta->rx_stats.last_rx + exp_rsn) &&
 		     sta->sta_state != IEEE80211_STA_AUTHORIZED)) {
 			sta_dbg(sta->sdata, "expiring inactive %sSTA %pM\n",
 				sta->sta_state != IEEE80211_STA_AUTHORIZED ?