The MFC device driver is a v4l2 driver which can encode/decode video
raw/elementary streams and has support for all popular video codecs.
The driver's watchdog_workqueue has been replaced with system_wq since
it queues a single work item, &dev->watchdog_work, which calls for no
ordering requirement. The work item is involved in running the watchdog
timer and is not being used on a memory reclaim path.
Work item has been flushed in s5p_mfc_remove() to ensure
that there are no pending tasks while disconnecting the driver.