mainboard/[^a-p]*: Remove copyright notices

They're listed in AUTHORS and often incorrect anyway, for example:
- What's a "Copyright $year-present"?
- Which incarnation of Google (Inc, LLC, ...) is the current
  copyright holder?
- People sometimes have their editor auto-add themselves to files even
  though they only deleted stuff
- Or they let the editor automatically update the copyright year,
  because why not?
- Who is the copyright holder "The coreboot project Authors"?
- Or "Generated Code"?

Sidestep all these issues by simply not putting these notices in
individual files, let's list all copyright holders in AUTHORS instead
and use the git history to deal with the rest.

Change-Id: I18e513cefc373b1cd70d31d1159928cc948a8476
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39609
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
Reviewed-by: Tristan Corrick <tristan@corrick.kiwi>

src/mainboard/samsung/stumpy/early_init.c

@@ -1,8 +1,6 @@
 /*
  * This file is part of the coreboot project.
  *
- * Copyright (C) 2007-2010 coresystems GmbH
- * Copyright (C) 2011 The ChromiumOS Authors.  All rights reserved.
  *
  * 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