drm/i915/gen9: Implement WaDisablePartialInstShootdown

v2: Dont add WaDisableThreadStallDopClockGating as not SKL WA. (Found
by Damien Lespiau)

Signed-off-by: Nick Hoath <nicholas.hoath@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
[danvet: Bikeshed commit message a bit as per Damien's suggestions.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -875,6 +875,13 @@ static int chv_init_workarounds(struct intel_engine_cs *ring)
 
 static int gen9_init_workarounds(struct intel_engine_cs *ring)
 {
+	struct drm_device *dev = ring->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	/* WaDisablePartialInstShootdown:skl */
+	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
+			  PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);
+
 	return 0;
 }