drm/i915/rkl: Use revid->stepping tables

Switch RKL to use a revid->stepping table as we're trying to do on all
platforms going forward.

Bspec: 44501
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210713193635.3390052-10-matthew.d.roper@intel.com