• Split transmit queue into one for each type. Apparently there will

be a race when using a single active queue for all transmit types.

• Last argument of usb_pause_mtx() is ticks and not milliseconds.
• Remove unused watchdog.
• Remove some unused fields from the RSU softc structure.
• Workaround usbd_transfer_start() recursion from inside of completion

callback.

MFC after: 3 days