drm/i915: unregister interfaces first in unload

We first need to make sure no one else can get at us anymore,
before we can proceed to tear down all the datastructures.

Just a small step towards eventually the perfect unload code ...
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20170714224656.6431-3-daniel.vetter@ffwll.ch

drivers/gpu/drm/i915/i915_drv.c

@@ -1375,6 +1375,8 @@ void i915_driver_unload(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct pci_dev *pdev = dev_priv->drm.pdev;
 
+	i915_driver_unregister(dev_priv);
+
 	if (i915_gem_suspend(dev_priv))
 		DRM_ERROR("failed to idle hardware; continuing to unload!\n");
 
@@ -1384,8 +1386,6 @@ void i915_driver_unload(struct drm_device *dev)
 
 	intel_gvt_cleanup(dev_priv);
 
-	i915_driver_unregister(dev_priv);
-
 	drm_vblank_cleanup(dev);
 
 	intel_modeset_cleanup(dev);