net: sched: htb: remove redundant resource cleanup in htb_init()

If htb_init() fails, qdisc_create() invokes htb_destroy() to clear
resources. Therefore, remove redundant resource cleanup in htb_init().

Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>