mainboard/apple: add license headers

Change-Id: Id9487212411e5c237d26eb4e5663135f7d0720d1
Signed-off-by: Noah Glovsky <noah.glovsky@watershedschool.org>
Reviewed-on: https://review.coreboot.org/14425
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/src/mainboard/apple/macbookair4_2/hda_verb.c b/src/mainboard/apple/macbookair4_2/hda_verb.c
index 582eb6e..6ca5f51 100644
--- a/src/mainboard/apple/macbookair4_2/hda_verb.c
+++ b/src/mainboard/apple/macbookair4_2/hda_verb.c
@@ -1,3 +1,16 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * 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.
+ */
+
 #include <device/azalia_device.h>
 
 const u32 cim_verb_data[] = {