drm/i915/panel: Track temporary rpm wakeref

Keep track of the temporary rpm wakeref used for panel backlight access,
so that we can cancel it immediately upon release and so more clearly
identify leaks.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-13-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_panel.c

@@ -1203,17 +1203,18 @@ static int intel_backlight_device_get_brightness(struct backlight_device *bd)
 	struct intel_connector *connector = bl_get_data(bd);
 	struct drm_device *dev = connector->base.dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
+	intel_wakeref_t wakeref;
 	u32 hw_level;
 	int ret;
 
-	intel_runtime_pm_get(dev_priv);
+	wakeref = intel_runtime_pm_get(dev_priv);
 	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
 
 	hw_level = intel_panel_get_backlight(connector);
 	ret = scale_hw_to_user(connector, hw_level, bd->props.max_brightness);
 
 	drm_modeset_unlock(&dev->mode_config.connection_mutex);
-	intel_runtime_pm_put_unchecked(dev_priv);
+	intel_runtime_pm_put(dev_priv, wakeref);
 
 	return ret;
 }