SL811 Device detected after removal used to be working in linux-2.6.22
but then broke somewhere between 2.6.22 and 2.6.28. Current
hub_port_connect_change() in drivers/usb/core/hub.c won't call
usb_disconnect() in case the SL811 driver sets portstatus
USB_PORT_FEAT_CONNECTION upon removal.
AFAIK the SL811 has only a combined Device Insert/Remove
detection bit, therefore use a count to distinguish insert or remove.