net: sched: htb: fix htb_classify() kernel-doc

Fix W=1 kernel-doc warning:

net/sched/sch_htb.c:214: warning: expecting prototype for htb_classify(). Prototype was for HTB_DIRECT() instead

by moving the HTB_DIRECT() macro above the function.
Add kernel-doc notation for function parameters as well.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>