batman-adv: fix warning in function batadv_v_elp_get_throughput

[ Upstream commit ca8c3b922e7032aff6cc3fd05548f4df1f3df90e ]

When CONFIG_CFG80211 isn't enabled the compiler correcly warns about
'sinfo.pertid' may be unused. It can also happen for other error
conditions that it not warn about.

net/batman-adv/bat_v_elp.c: In function ‘batadv_v_elp_get_throughput.isra.0’:
include/net/cfg80211.h:6370:13: warning: ‘sinfo.pertid’ may be used
 uninitialized in this function [-Wmaybe-uninitialized]
  kfree(sinfo->pertid);
        ~~~~~^~~~~~~~

Rework so that we only release '&sinfo' if cfg80211_get_station returns
zero.

Fixes: 7d652669b61d ("batman-adv: release station info tidstats")
Signed-off-by: NAnders Roxell <anders.roxell@linaro.org>
Signed-off-by: NSven Eckelmann <sven@narfation.org>
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: NSasha Levin <sashal@kernel.org>

net/batman-adv/bat_v_elp.c

@@ -104,8 +104,10 @@ static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
 
 		ret = cfg80211_get_station(real_netdev, neigh->addr, &sinfo);
 
-		/* free the TID stats immediately */
-		cfg80211_sinfo_release_content(&sinfo);
+		if (!ret) {
+			/* free the TID stats immediately */
+			cfg80211_sinfo_release_content(&sinfo);
+		}
 
 		dev_put(real_netdev);
 		if (ret == -ENOENT) {