nfit/ars: Allow root to busy-poll the ARS state machine
The ARS implementation implements exponential back-off on the poll
interval to prevent high-frequency access to the DIMM / platform
interface. Depending on when the ARS completes the poll interval may
exceed the completion event by minutes. Allow root to reset the timeout
each time it probes the status. A one-second timeout is still enforced,
but root can otherwise can control the poll interval.
Fixes: bc6ba8085842 ("nfit, address-range-scrub: rework and simplify ARS...") Cc: <stable@vger.kernel.org> Reported-by: Erwin Tsaur <erwin.tsaur@oracle.com> Reviewed-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>