drm/i915/fbdev: Use the PLANE_HAS_FENCE flags from the time of pinning

Use the information about the fence state from the time of pinning to
determine if the fbdev writes are going through a fence. This avoids any
confusion in cases where the fence may appear or disappear unconnected
to the use by fbdev.

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180220134208.24988-3-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_fbdev.c

@@ -48,7 +48,8 @@
 static void intel_fbdev_invalidate(struct intel_fbdev *ifbdev)
 {
 	struct drm_i915_gem_object *obj = ifbdev->fb->obj;
-	unsigned int origin = ifbdev->vma->fence ? ORIGIN_GTT : ORIGIN_CPU;
+	unsigned int origin =
+		ifbdev->vma_flags & PLANE_HAS_FENCE ? ORIGIN_GTT : ORIGIN_CPU;
 
 	intel_fb_obj_invalidate(obj, origin);
 }