treewide: Convert more license headers to SPDX style

Change-Id: Ia3de79c7d71049da00ed108829eac6cb49ff3ed6
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41205
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/drivers/spi/tpm/tpm.c b/src/drivers/spi/tpm/tpm.c
index c47aed3..24851d1 100644
--- a/src/drivers/spi/tpm/tpm.c
+++ b/src/drivers/spi/tpm/tpm.c
@@ -1,9 +1,5 @@
-/*
- * Copyright 2016 The Chromium OS Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- *
- * This is a driver for a SPI interfaced TPM2 device.
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* This is a driver for a SPI interfaced TPM2 device.
  *
  * It assumes that the required SPI interface has been initialized before the
  * driver is started. A 'sruct spi_slave' pointer passed at initialization is