knc: Bugfix - good shares wrongly reported as HW errors.
  Root cause of the problem: several work items were assigned the same
  work_id in the active works queue of the knc driver. Thus when good
  nonce report arrived from the FPGA, wrong work item was picked up from
  the queue, and submit_nonce evaluated that as an error.
  Fix: Limit the work_id counter update rate. Update it only to the number of
  works actually consumed by the FPGA, not to the number of works send.