nfit, address-range-scrub: add module option to skip initial ars

After attempting to quickly retrieve known errors the kernel proceeds to
kick off a long running ARS. Add a module option to disable this
behavior at initialization time, or at new region discovery time.
Otherwise, ARS can be started manually regardless of the state of this
setting.

Co-developed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>