treewide: Unify Google branding

Branding changes to unify and update Chrome OS to ChromeOS (removing the
space).

This CL also includes changing Chromium OS to ChromiumOS as well.

BUG=None
TEST=N/A

Change-Id: I39af9f1069b62747dbfeebdd62d85fabfa655dcd
Signed-off-by: Jon Murphy <jpmurphy@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65479
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>

payloads/libpayload/drivers/serial/ipq806x.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 Chromium OS authors
+ * Copyright (c) 2014 ChromiumOS authors
  */
 
 #include <libpayload.h>