license: add spdx identifier to all files

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ifddd07cc0eb5edeb2dcb410747073d68c6631cb1
diff --git a/tests/bios_table_iter.c b/tests/bios_table_iter.c
index f8da402..1e9840a 100644
--- a/tests/bios_table_iter.c
+++ b/tests/bios_table_iter.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */
 /* Force elision of assert() */
 #ifndef NDEBUG
 #define NDEBUG