drm/i915: add a common connector type independent destroy hook

Almost all of the connector destroy functions do the same thing. The
differences are in the edid, detect_edid and panel cleanups, but those
are safely NULL when not initialized. Roll out a common connector
destroy hook.

Inspired by commit bc3213c444 ("drm/i915: Drop the eDP check from
intel_dp_connector_destroy()").

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181009141103.20387-1-jani.nikula@intel.com

drivers/gpu/drm/i915/vlv_dsi.c

@@ -1642,16 +1642,6 @@ static int intel_dsi_get_modes(struct drm_connector *connector)
 	return 1;
 }
 
-static void intel_dsi_connector_destroy(struct drm_connector *connector)
-{
-	struct intel_connector *intel_connector = to_intel_connector(connector);
-
-	DRM_DEBUG_KMS("\n");
-	intel_panel_fini(&intel_connector->panel);
-	drm_connector_cleanup(connector);
-	kfree(connector);
-}
-
 static void intel_dsi_encoder_destroy(struct drm_encoder *encoder)
 {
 	struct intel_dsi *intel_dsi = enc_to_intel_dsi(encoder);
@@ -1676,7 +1666,7 @@ static const struct drm_connector_helper_funcs intel_dsi_connector_helper_funcs
 static const struct drm_connector_funcs intel_dsi_connector_funcs = {
 	.late_register = intel_connector_register,
 	.early_unregister = intel_connector_unregister,
-	.destroy = intel_dsi_connector_destroy,
+	.destroy = intel_connector_destroy,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.atomic_get_property = intel_digital_connector_atomic_get_property,
 	.atomic_set_property = intel_digital_connector_atomic_set_property,