SPDX: Convert all of our single license tags to Linux Kernel style

When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from. So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry. Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents. There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>

tools/ifdtool: Support writing multiple files (-w) simultaneously

Currently ifdtool only supports writing one file (-w) at a time.
This looks verbose when generating u-boot.rom for x86 targets.
This change allows at most 16 files to be written simultaneously.

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

x86: Add ifdtool for working with Intel Flash Descriptor ROM images

Newer Intel chips require a Management Engine which requires a particular
format for the SPI flash that contains the boot loader. Add a tool that
supports creating and modifying these ROM images.

This tool is from Chrome OS but has been cleaned up to use U-Boot style
and to add comments. A few features have been added also.

Signed-off-by: Simon Glass <sjg@chromium.org>