drm/i915: Inject a failure point when registering a connector

Check we can handle a late display load failure where the final act of
registering the connector fails.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181010123833.16797-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_connector.c

@@ -107,8 +107,15 @@ int intel_connector_register(struct drm_connector *connector)
 	if (ret)
 		goto err;
 
+	if (i915_inject_load_failure()) {
+		ret = -EFAULT;
+		goto err_backlight;
+	}
+
 	return 0;
 
+err_backlight:
+	intel_backlight_device_unregister(intel_connector);
 err:
 	return ret;
 }