drm: omapdrm: Add missing check for alloc_ordered_workqueue

As it may return NULL pointer and cause NULL pointer dereference. Add check
for the return value of alloc_ordered_workqueue.

Cc: stable@vger.kernel.org
Fixes: 2f95bc6d ("drm: omapdrm: Perform initialization/cleanup at probe/remove time")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240808061336.2796729-1-make24@iscas.ac.cn

drivers/gpu/drm/omapdrm/omap_drv.c

@@ -695,6 +695,10 @@ static int omapdrm_init(struct omap_drm_private *priv, struct device *dev)
 	soc = soc_device_match(omapdrm_soc_devices);
 	priv->omaprev = soc ? (uintptr_t)soc->data : 0;
 	priv->wq = alloc_ordered_workqueue("omapdrm", 0);
+	if (!priv->wq) {
+		ret = -ENOMEM;
+		goto err_alloc_workqueue;
+	}
 
 	mutex_init(&priv->list_lock);
 	INIT_LIST_HEAD(&priv->obj_list);
@@ -753,6 +757,7 @@ static int omapdrm_init(struct omap_drm_private *priv, struct device *dev)
 	drm_mode_config_cleanup(ddev);
 	omap_gem_deinit(ddev);
 	destroy_workqueue(priv->wq);
+err_alloc_workqueue:
 	omap_disconnect_pipelines(ddev);
 	drm_dev_put(ddev);
 	return ret;