fix rt-thread once thread delete

class/hub/usbh_hub.c

@@ -449,7 +449,7 @@ static void usbh_hubport_enumerate_thread(void *argument)
         usbh_hubport_release(child);
         USB_LOG_ERR("Port %u enumerate fail\r\n", child->port);
     }
-    usb_osal_thread_delete(child->thread);
+    usb_osal_thread_delete(NULL);
 }
 
 static void usbh_hub_events(struct usbh_hub *hub)

osal/usb_osal_rtthread.c

@@ -18,6 +18,10 @@ usb_osal_thread_t usb_osal_thread_create(const char *name, uint32_t stack_size,
 
 void usb_osal_thread_delete(usb_osal_thread_t thread)
 {
+    if (thread == NULL) {
+        return;
+    }
+
     rt_thread_delete(thread);
 }