net: sched: sch: add extack to change class

This patch adds extack support for class change callback api. This prepares
to handle extack support inside each specific class implementation.

Cc: David Ahern <dsahern@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_sfb.c

@@ -645,7 +645,8 @@ static void sfb_unbind(struct Qdisc *sch, unsigned long arg)
 }
 
 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
-			    struct nlattr **tca, unsigned long *arg)
+			    struct nlattr **tca, unsigned long *arg,
+			    struct netlink_ext_ack *extack)
 {
 	return -ENOSYS;
 }