drm/i915/bdw: Do not write the Semaphore Sync Registers in GEN8+

These do not exist anymore.

Spotted while reading through intel_ringbuffer.c
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1746,14 +1746,15 @@ int intel_ring_cacheline_align(struct intel_engine_cs *ring)
 
 void intel_ring_init_seqno(struct intel_engine_cs *ring, u32 seqno)
 {
-	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+	struct drm_device *dev = ring->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	BUG_ON(ring->outstanding_lazy_seqno);
 
-	if (INTEL_INFO(ring->dev)->gen >= 6) {
+	if (INTEL_INFO(dev)->gen == 6 || INTEL_INFO(dev)->gen == 7) {
 		I915_WRITE(RING_SYNC_0(ring->mmio_base), 0);
 		I915_WRITE(RING_SYNC_1(ring->mmio_base), 0);
-		if (HAS_VEBOX(ring->dev))
+		if (HAS_VEBOX(dev))
 			I915_WRITE(RING_SYNC_2(ring->mmio_base), 0);
 	}