drm/i915: Bring GPU Freq to min while suspending.

We might be leaving the PGU Frequency (and thus vnn) high during the suspend.
Flusing the delayed work queue should take care of this.
Signed-off-by: NDeepak S <deepak.s@linux.intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -4554,7 +4554,7 @@ i915_gem_suspend(struct drm_device *dev)
 
 	del_timer_sync(&dev_priv->gpu_error.hangcheck_timer);
 	cancel_delayed_work_sync(&dev_priv->mm.retire_work);
-	cancel_delayed_work_sync(&dev_priv->mm.idle_work);
+	flush_delayed_work(&dev_priv->mm.idle_work);
 
 	return 0;