Revert "drm/i915/dg2: extend Wa_1409120013 to DG2"

This reverts commit 487970e.

Updated bspec and workaround database note Wa_1409120013 is not needed
for DG2 (or any Xe_LPD) platform. Simply check by display version 12.

v2: Simplify condition check to display version (Matt Roper)

Cc: Matt Atwood <matthew.s.atwood@intel.com>
Cc: Clint Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220907232541.1720966-1-lucas.demarchi@intel.com
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/intel_pm.c

@@ -7466,9 +7466,8 @@ static void icl_init_clock_gating(struct drm_i915_private *dev_priv)
 
 static void gen12lp_init_clock_gating(struct drm_i915_private *dev_priv)
 {
-	/* Wa_1409120013:tgl,rkl,adl-s,dg1,dg2 */
-	if (IS_TIGERLAKE(dev_priv) || IS_ROCKETLAKE(dev_priv) ||
-	    IS_ALDERLAKE_S(dev_priv) || IS_DG1(dev_priv) || IS_DG2(dev_priv))
+	/* Wa_1409120013 */
+	if (DISPLAY_VER(dev_priv) == 12)
 		intel_uncore_write(&dev_priv->uncore, ILK_DPFC_CHICKEN(INTEL_FBC_A),
 				   DPFC_CHICKEN_COMP_DUMMY_PIXEL);