x86: Fix a header nit in x86-chromebook.h

There is an extra line in the comment in the header. Remove it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

include/configs/x86-chromebook.h

 /*
- *
  * Copyright (c) 2015 Google, Inc
  *
  * SPDX-License-Identifier:	GPL-2.0+