sch_htb: fix doc warning in htb_add_to_wait_tree()

Add description for parameters of htb_add_to_wait_tree() to fix
gcc W=1 warnings:

net/sched/sch_htb.c:308: warning: Function parameter or member 'q' not described in 'htb_add_to_wait_tree'
net/sched/sch_htb.c:308: warning: Function parameter or member 'cl' not described in 'htb_add_to_wait_tree'
net/sched/sch_htb.c:308: warning: Function parameter or member 'delay' not described in 'htb_add_to_wait_tree'
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_htb.c

@@ -301,6 +301,9 @@ static void htb_add_to_id_tree(struct rb_root *root,
 
 /**
  * htb_add_to_wait_tree - adds class to the event queue with delay
+ * @q: the priority event queue
+ * @cl: the class to add
+ * @delay: delay in microseconds
  *
  * The class is added to priority event queue to indicate that class will
  * change its mode in cl->pq_key microseconds. Make sure that class is not