watchdog: Fix memleak in watchdog_cdev_register

When watchdog_kworker is NULL, we should free wd_data
before the function returns to prevent memleak.

Fixes: 664a3923 ("watchdog: Introduce hardware maximum heartbeat in watchdog core")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200824024001.25474-1-dinghao.liu@zju.edu.cnSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/watchdog_dev.c

@@ -994,8 +994,10 @@ static int watchdog_cdev_register(struct watchdog_device *wdd)
 	wd_data->wdd = wdd;
 	wdd->wd_data = wd_data;
 
-	if (IS_ERR_OR_NULL(watchdog_kworker))
+	if (IS_ERR_OR_NULL(watchdog_kworker)) {
+		kfree(wd_data);
 		return -ENODEV;
+	}
 
 	device_initialize(&wd_data->dev);
 	wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);