drm/i915: Enable semaphores for legacy submission on gen8

We have sufficient evidence from igt to support that semaphores are in
a working state. Enabling semaphores now for legacy provides a better
comparison of execlists against legacy ring submission.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461928823-10298-6-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_drv.c

@@ -542,10 +542,6 @@ bool i915_semaphore_is_enabled(struct drm_device *dev)
 	if (i915.enable_execlists)
 		return false;
 
-	/* Until we get further testing... */
-	if (IS_GEN8(dev))
-		return false;
-
 #ifdef CONFIG_INTEL_IOMMU
 	/* Enable semaphores on SNB when IO remapping is off */
 	if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)