ath10k: fix memory leak of tpc_stats

Currently tpc_stats is allocated and is leaked on the return
path if num_tx_chain is greater than WMI_TPC_TX_N_CHAIN. Avoid
this leak by performing the check on num_tx_chain before the
allocation of tpc_stats.

Detected by CoverityScan, CID#1469422 ("Resource Leak")
Fixes: 4b190675 ("ath10k: fix kernel panic while reading tpc_stats")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

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

@@ -4602,10 +4602,6 @@ void ath10k_wmi_event_pdev_tpc_config(struct ath10k *ar, struct sk_buff *skb)
 
 	ev = (struct wmi_pdev_tpc_config_event *)skb->data;
 
-	tpc_stats = kzalloc(sizeof(*tpc_stats), GFP_ATOMIC);
-	if (!tpc_stats)
-		return;
-
 	num_tx_chain = __le32_to_cpu(ev->num_tx_chain);
 
 	if (num_tx_chain > WMI_TPC_TX_N_CHAIN) {
@@ -4614,6 +4610,10 @@ void ath10k_wmi_event_pdev_tpc_config(struct ath10k *ar, struct sk_buff *skb)
 		return;
 	}
 
+	tpc_stats = kzalloc(sizeof(*tpc_stats), GFP_ATOMIC);
+	if (!tpc_stats)
+		return;
+
 	ath10k_wmi_tpc_config_get_rate_code(rate_code, pream_table,
 					    num_tx_chain);