platform/x86/intel/ifs: add ABI documentation for IFS

platform/x86/intel/ifs: add ABI documentation for IFS

Add the sysfs attributes in ABI/testing for In-Field Scan.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20220506225410.1652287-12-tony.luck@intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>