pkt_sched: Annotate uninitialized var in sfq_enqueue()

Some gcc versions warn that ret may be used uninitialized in
sfq_enqueue(). It's a false positive, so let's annotate this.
Signed-off-by: NJarek Poplawski <jarkao2@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/sch_sfq.c

@@ -281,7 +281,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 	struct sfq_sched_data *q = qdisc_priv(sch);
 	unsigned int hash;
 	sfq_index x;
-	int ret;
+	int uninitialized_var(ret);
 
 	hash = sfq_classify(skb, sch, &ret);
 	if (hash == 0) {