drm/i915: don't check encoder at DP connector destroy()

By the time we call intel_dp_destroy (which destroys the connector)
the encoder may have been destroyed already, so if we use it we may be
reading some free memory. That happens in drm_mode_config_cleanup()
and also inside intel_dp_init_connector() when we detect a ghost eDP.

I also hope this may solve some random memory bugs.

Reported by kmemcheck.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Zoltan Nyul <zoltan.nyul@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -2683,13 +2683,14 @@ intel_dp_set_property(struct drm_connector *connector,
 static void
 intel_dp_destroy(struct drm_connector *connector)
 {
-	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	struct intel_connector *intel_connector = to_intel_connector(connector);
 
 	if (!IS_ERR_OR_NULL(intel_connector->edid))
 		kfree(intel_connector->edid);
 
-	if (is_edp(intel_dp))
+	/* Can't call is_edp() since the encoder may have been destroyed
+	 * already. */
+	if (connector->connector_type == DRM_MODE_CONNECTOR_eDP)
 		intel_panel_fini(&intel_connector->panel);
 
 	drm_sysfs_connector_remove(connector);