*/mb/google/volteer/**/gpio.h: Fix up license header

There's a `GPL-2.0-or-later` version of this file in volteer2, so use it
in place of these weirdly-licensed files.

Change-Id: Icde2f6539d9c726d6967350f74e7bc015e01e7b5
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43855
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/mainboard/google/volteer/variants/delbin/include/variant/gpio.h

@@ -1,15 +1,4 @@
-/*
+/* SPDX-License-Identifier: GPL-2.0-or-later */
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
- * GNU General Public License for more details.
- *
- * SPDX-License-Identifier: GPL-2.0-or-later
- */
 
 #ifndef VARIANT_GPIO_H
 #define VARIANT_GPIO_H

util/mainboard/google/volteer/template/include/variant/gpio.h

@@ -1,15 +1,4 @@
-/*
+/* SPDX-License-Identifier: GPL-2.0-or-later */
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
- * GNU General Public License for more details.
- *
- * SPDX-License-Identifier: GPL-2.0-or-later
- */
 
 #ifndef VARIANT_GPIO_H
 #define VARIANT_GPIO_H