net_sched: fix error return code in fw_change_attrs()

The error code was not set if change indev fail, so the error
condition wasn't reflected in the return value. Fix to return a
negative error code from this error handling case instead of 0.

Fixes: 2519a602c273 ('net_sched: optimize tcf_match_indev()')
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_fw.c

@@ -209,8 +209,10 @@ fw_change_attrs(struct net *net, struct tcf_proto *tp, struct fw_filter *f,
 	if (tb[TCA_FW_INDEV]) {
 		int ret;
 		ret = tcf_change_indev(net, tb[TCA_FW_INDEV]);
-		if (ret < 0)
+		if (ret < 0) {
+			err = ret;
 			goto errout;
+		}
 		f->ifindex = ret;
 	}
 #endif /* CONFIG_NET_CLS_IND */