drm: Check polling initialized before enabling in drm_helper_probe_single_connector_modes

In function drm_helper_probe_single_connector_modes() when we enable
polling again, if it is already uninitialized, a warning is reported.
This patch fixes the warning message by checking if poll is initialized
before enabling it.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202401191128.db8423f1-oliver.sang@intel.comSigned-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1706856224-9725-1-git-send-email-shradhagupta@linux.microsoft.com

drivers/gpu/drm/drm_probe_helper.c

@@ -622,7 +622,11 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 					 0);
 	}
 
-	/* Re-enable polling in case the global poll config changed. */
+	/*
+	 * Re-enable polling in case the global poll config changed but polling
+	 * is still initialized.
+	 */
+	if (dev->mode_config.poll_enabled)
 		drm_kms_helper_poll_enable(dev);
 
 	if (connector->status == connector_status_disconnected) {