net: sched: integer overflow fix

[ Upstream commit d2fe85da52e89b8012ffad010ef352a964725d5f ]

Fixed integer overflow in function htb_dequeue

Signed-off-by: Stefan Hasko <hasko.stevo@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>