A RECONFIGURE event may trigger an allocation query from upstream on the v4l2jpegenc event. If the format is the same, the format on the encoder is not changed and the processing thread running.
In this case, the element should switch to copy mode to avoid costly reallocation of the V4L2 buffers.
As the processing thread of the element is not stopped, it doesn't have to be restarted. However, the internal pool may have been deactivated by an upstream element.
The v4l2videoenc always has to ensure that the CAPTURE pool is active when a buffer arrives.
Fixes: #1782