drm/i915/dg2: s/DISP_STEPPING/DISPLAY_STEPPING/

Commit cd0fcf5a ("drm/i915: rename DISP_STEPPING->DISPLAY_STEP and
GT_STEPPING->GT_STEP") renamed all platforms' display stepping tests,
but the DG2 patches were still in-flight at that time and did not
incorporate the new naming scheme.  Rename DG2's macro now for
consistency with other platforms.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211116174818.2128062-2-matthew.d.roper@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -1595,7 +1595,7 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
 	(IS_SUBPLATFORM(__i915, INTEL_DG2, INTEL_SUBPLATFORM_##variant) && \
 	 IS_GT_STEP(__i915, since, until))
 
-#define IS_DG2_DISP_STEP(__i915, since, until) \
+#define IS_DG2_DISPLAY_STEP(__i915, since, until) \
 	(IS_DG2(__i915) && \
 	 IS_DISPLAY_STEP(__i915, since, until))