ath10k: improve beacon submission latency

The patch prevents beacon misses in some case of
heavy load on a system.

If a beacon can't be transmitted directly from an
SWBA event it will be left in arvif->beacon and
transmission will be retried once TX credits
become available.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index 8b9fb66..6c3e9d1 100644
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -2075,6 +2075,13 @@
 
 	mutex_lock(&ar->conf_mutex);
 
+	spin_lock_bh(&ar->data_lock);
+	if (arvif->beacon) {
+		dev_kfree_skb_any(arvif->beacon);
+		arvif->beacon = NULL;
+	}
+	spin_unlock_bh(&ar->data_lock);
+
 	ar->free_vdev_map |= 1 << (arvif->vdev_id);
 
 	if (arvif->vdev_type == WMI_VDEV_TYPE_AP) {