components/bt: Update licenses

examples/bluetooth/hci/controller_hci_uart_esp32c3/main/uhci_uart_demo.c

@@ -1,10 +1,8 @@
 /*
-   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.
-*/
+ * SPDX-FileCopyrightText: 2021 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
 
 #include <string.h>
 #include "esp_private/periph_ctrl.h" // for enabling UHCI module, remove it after UHCI driver is released