cfg80211: fix error return code in cfg80211_init()

Fix to return a negative error code from the error handling
case instead of 0, as returned elsewhere in this function.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/core.c

@@ -1096,8 +1096,10 @@ static int __init cfg80211_init(void)
 		goto out_fail_reg;
 
 	cfg80211_wq = create_singlethread_workqueue("cfg80211");
-	if (!cfg80211_wq)
+	if (!cfg80211_wq) {
+		err = -ENOMEM;
 		goto out_fail_wq;
+	}
 
 	return 0;