drm/i915/rpl-p: Add stepping info

Add stepping-substepping info in accordance to bpsec changes.

Bspec: 55376

Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Matt Atwood <matthew.s.atwood@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221117214132.152061-1-matthew.s.atwood@intel.com