gptimer: clean up hal and ll for driver-ng

examples/peripherals/timer_group/main/timer_group_example_main.c

@@ -1,11 +1,9 @@
-/* General Purpose Timer example
+/*
+ * SPDX-FileCopyrightText: 2010-2021 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: CC0-1.0
+ */
 
-   This example code is in the Public Domain (or CC0 licensed, at your option.)
-
-   Unless required by applicable law or agreed to in writing, this
-   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-   CONDITIONS OF ANY KIND, either express or implied.
-*/
 #include <stdio.h>
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"