ath10k: plug memory leak on beacon tx

If beacon tx command failed the wmi command buffer
was not freed. This led to OOM in the long run.
This became aparent when stress testing
multi-BSSID.
Reported-By: Tomasz Skapski <tomasz.skapski@tieto.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

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

@@ -3092,6 +3092,7 @@ int ath10k_wmi_beacon_send_nowait(struct ath10k *ar,
 {
 	struct wmi_bcn_tx_cmd *cmd;
 	struct sk_buff *skb;
+	int ret;
 
 	skb = ath10k_wmi_alloc_skb(sizeof(*cmd) + arg->bcn_len);
 	if (!skb)
@@ -3104,7 +3105,11 @@ int ath10k_wmi_beacon_send_nowait(struct ath10k *ar,
 	cmd->hdr.bcn_len  = __cpu_to_le32(arg->bcn_len);
 	memcpy(cmd->bcn, arg->bcn, arg->bcn_len);
 
-	return ath10k_wmi_cmd_send_nowait(ar, skb, ar->wmi.cmd->bcn_tx_cmdid);
+	ret = ath10k_wmi_cmd_send_nowait(ar, skb, ar->wmi.cmd->bcn_tx_cmdid);
+	if (ret)
+		dev_kfree_skb(skb);
+
+	return ret;
 }
 
 static void ath10k_wmi_pdev_set_wmm_param(struct wmi_wmm_params *params,