cw1200: fix missing unlock on error in cw1200_hw_scan()

BugLink: https://bugs.launchpad.net/bugs/1830176

commit 51c8d241 upstream.

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>
[iwamatsu: Change the patching file from drivers/net/wireless/st/cw1200/scan.c to
drivers/net/wireless/cw1200/scan.c]
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/wireless/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)
 		memcpy(skb_put(frame.skb, req->ie_len), req->ie, req->ie_len);