mb/emulation/qemu-aarch64: Fix up license header

Change-Id: I9730680a8359407a2a03dbb7243a6547420e1f39
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43856
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/emulation/qemu-aarch64/mainboard.c

@@ -1,8 +1,4 @@
-/*
+/* SPDX-License-Identifier: GPL-2.0-or-later */
- *
- *
- * SPDX-License-Identifier: GPL-2.0-or-later
- */
 
 #include <cbmem.h>
 #include <ramdetect.h>