Add missing license header to udelay.c

I'm self-ack'ing this, as the origin of the code in udelay.c (and thus
the license and copyright owner) is pretty clear.

The code which is now in udelay.c was split out from flash_rom.c in r1428,
and flash_rom.c, in turn, has been around since the beginning and had a
'Copyright 2000 Silicon Integrated System Corporation' line as well as the
usual GPLv2-or-later license header.

Corresponding to flashrom svn r135 and coreboot v2 svn r2767.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>

udelay.c

@@ -1,3 +1,23 @@
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright 2000 Silicon Integrated System Corporation
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
 #include <sys/time.h>
 #include <stdio.h>
 #include "flash.h"