cw1200: fix missing unlock on error in cw1200_hw_scan()

Add the missing unlock before return from function cw1200_hw_scan()
in the error handling case.

Fixes: 4f68ef64 ("cw1200: Fix concurrency use-after-free bugs in cw1200_hw_scan()")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/st/cw1200/scan.c

@@ -84,8 +84,11 @@ int cw1200_hw_scan(struct ieee80211_hw *hw,
 
 	frame.skb = ieee80211_probereq_get(hw, priv->vif->addr, NULL, 0,
 		req->ie_len);
-	if (!frame.skb)
+	if (!frame.skb) {
+		mutex_unlock(&priv->conf_mutex);
+		up(&priv->scan.lock);
 		return -ENOMEM;
+	}
 
 	if (req->ie_len)
 		skb_put_data(frame.skb, req->ie, req->ie_len);