ath10k: fix num_legacy_stations tracking

If a station was reassociated, i.e. due to change
of supported rates update via sta_rc_update() the
num_legacy_stations would be (incorrectly) bumped
up leading to unbalanced usage of the var. This in
turn could lock rtscts protection up as enabled.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/mac.c

@@ -1615,7 +1615,7 @@ static int ath10k_station_assoc(struct ath10k *ar, struct ath10k_vif *arvif,
 		return ret;
 	}
 
-	if (!sta->wme) {
+	if (!sta->wme && !reassoc) {
 		arvif->num_legacy_stations++;
 		ret  = ath10k_recalc_rtscts_prot(arvif);
 		if (ret) {