net: fix suspicious rcu_dereference_check in net/sched/sch_fq_codel.c

commit 46e5da40 (net: qdisc: use rcu prefix and silence
 sparse warnings) triggers a spurious warning:

net/sched/sch_fq_codel.c:97 suspicious rcu_dereference_check() usage!

The code should be using the _bh variant of rcu_dereference.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_fq_codel.c

@@ -94,7 +94,7 @@ static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
 	    TC_H_MIN(skb->priority) <= q->flows_cnt)
 		return TC_H_MIN(skb->priority);
 
-	filter = rcu_dereference(q->filter_list);
+	filter = rcu_dereference_bh(q->filter_list);
 	if (!filter)
 		return fq_codel_hash(q, skb) + 1;