ath6kl: wmi: fix an error code in ath6kl_wmi_sync_point()

This error path is unlikely because of it checked for NULL and
returned -ENOMEM earlier in the function.  But it should return
an error code here as well if we ever do hit it because of a
race condition or something.

Fixes: bdcd8170 ("Add ath6kl cleaned up driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210813113438.GB30697@kili

drivers/net/wireless/ath/ath6kl/wmi.c

@@ -2504,8 +2504,10 @@ static int ath6kl_wmi_sync_point(struct wmi *wmi, u8 if_idx)
 		goto free_data_skb;
 
 	for (index = 0; index < num_pri_streams; index++) {
-		if (WARN_ON(!data_sync_bufs[index].skb))
+		if (WARN_ON(!data_sync_bufs[index].skb)) {
+			ret = -ENOMEM;
 			goto free_data_skb;
+		}
 
 		ep_id = ath6kl_ac2_endpoint_id(wmi->parent_dev,
 					       data_sync_bufs[index].