drm: Remove struct drm_mode_config_funcs.output_poll_changed

The output_poll_changed hook in struct drm_mode_config_funcs is
unused. Remove it. The helper drm_client_dev_hotplug() implements
the callback's functionality.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20240812083000.337744-10-tzimmermann@suse.de

drivers/gpu/drm/drm_probe_helper.c

@@ -714,7 +714,7 @@ EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
  * @dev: drm_device whose connector state changed
  *
  * This function fires off the uevent for userspace and also calls the
- * output_poll_changed function, which is most commonly used to inform the fbdev
+ * client hotplug function, which is most commonly used to inform the fbdev
  * emulation code and allow it to update the fbcon output configuration.
  *
  * Drivers should call this from their hotplug handling code when a change is
@@ -730,11 +730,7 @@ EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
  */
 void drm_kms_helper_hotplug_event(struct drm_device *dev)
 {
-	/* send a uevent + call fbdev */
 	drm_sysfs_hotplug_event(dev);
-	if (dev->mode_config.funcs->output_poll_changed)
-		dev->mode_config.funcs->output_poll_changed(dev);
-
 	drm_client_dev_hotplug(dev);
 }
 EXPORT_SYMBOL(drm_kms_helper_hotplug_event);
@@ -750,11 +746,7 @@ void drm_kms_helper_connector_hotplug_event(struct drm_connector *connector)
 {
 	struct drm_device *dev = connector->dev;
 
-	/* send a uevent + call fbdev */
 	drm_sysfs_connector_hotplug_event(connector);
-	if (dev->mode_config.funcs->output_poll_changed)
-		dev->mode_config.funcs->output_poll_changed(dev);
-
 	drm_client_dev_hotplug(dev);
 }
 EXPORT_SYMBOL(drm_kms_helper_connector_hotplug_event);

include/drm/drm_mode_config.h

@@ -97,22 +97,6 @@ struct drm_mode_config_funcs {
 	 */
 	const struct drm_format_info *(*get_format_info)(const struct drm_mode_fb_cmd2 *mode_cmd);
 
-	/**
-	 * @output_poll_changed:
-	 *
-	 * Callback used by helpers to inform the driver of output configuration
-	 * changes.
-	 *
-	 * Drivers implementing fbdev emulation use drm_kms_helper_hotplug_event()
-	 * to call this hook to inform the fbdev helper of output changes.
-	 *
-	 * This hook is deprecated, drivers should instead implement fbdev
-	 * support with struct drm_client, which takes care of any necessary
-	 * hotplug event forwarding already without further involvement by
-	 * the driver.
-	 */
-	void (*output_poll_changed)(struct drm_device *dev);
-
 	/**
 	 * @mode_valid:
 	 *