drm/i915: Introduce i915_gem_object_finish_gpu()

... reincarnated from i915_gem_object_flush_gpu(). The semantic
difference is that after calling finish_gpu() the object no longer
resides in any GPU domain, and so will cause the GPU caches to be
invalidated if it is ever used again.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index aa43e7b..e32fb89 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1971,7 +1971,7 @@
 		 * This should only fail upon a hung GPU, in which case we
 		 * can safely continue.
 		 */
-		ret = i915_gem_object_flush_gpu(obj);
+		ret = i915_gem_object_finish_gpu(obj);
 		(void) ret;
 	}