drm/i915: fix non-DP-D eDP backlight cleanup and module reload

Backlight is initialized for eDP, but cleaned up only for eDP on DP-D
port. This leaves behind a dangling backlight interface on module unload on
machines that have eDP connected to something other than DP-D, and breaks
the backlight interface for subsequent module reloads. Fix the cleanup, and
thus module reload on affected machines.

Reported-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Tested-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -2370,8 +2370,9 @@ static void
 intel_dp_destroy(struct drm_connector *connector)
 {
 	struct drm_device *dev = connector->dev;
+	struct intel_dp *intel_dp = intel_attached_dp(connector);
 
-	if (intel_dpd_is_edp(dev))
+	if (is_edp(intel_dp))
 		intel_panel_destroy_backlight(dev);
 
 	drm_sysfs_connector_remove(connector);