drm/i915: Drop WaDisableRCPBUnitClockGating:vlv

Only early VLV steppings needed thist. Should no longer be relevant.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -4928,24 +4928,16 @@ static void valleyview_init_clock_gating(struct drm_device *dev)
 		   I915_READ(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG) |
 		   GEN7_SQ_CHICKEN_MBCUNIT_SQINTMOB);
 
-	/* According to the BSpec vol1g, bit 12 (RCPBUNIT) clock
-	 * gating disable must be set.  Failure to set it results in
-	 * flickering pixels due to Z write ordering failures after
-	 * some amount of runtime in the Mesa "fire" demo, and Unigine
-	 * Sanctuary and Tropics, and apparently anything else with
-	 * alpha test or pixel discard.
-	 *
+	/*
 	 * According to the spec, bit 13 (RCZUNIT) must be set on IVB.
 	 * This implements the WaDisableRCZUnitClockGating:vlv workaround.
 	 *
-	 * Also apply WaDisableVDSUnitClockGating:vlv and
-	 * WaDisableRCPBUnitClockGating:vlv.
+	 * Also apply WaDisableVDSUnitClockGating:vlv.
 	 */
 	I915_WRITE(GEN6_UCGCTL2,
 		   GEN7_VDSUNIT_CLOCK_GATE_DISABLE |
 		   GEN7_TDLUNIT_CLOCK_GATE_DISABLE |
-		   GEN6_RCZUNIT_CLOCK_GATE_DISABLE |
-		   GEN6_RCPBUNIT_CLOCK_GATE_DISABLE);
+		   GEN6_RCZUNIT_CLOCK_GATE_DISABLE);
 
 	/* WaDisableL3Bank2xClockGate:vlv */
 	I915_WRITE(GEN7_UCGCTL4, GEN7_L3BANK2X_CLOCK_GATE_DISABLE);