[XS] Change in coreboot[main]: src: Add missing SPDX license headers

[Nicholas Chin (Code Review)]

Attention is currently required from: Jason Nien, Martin Roth, Philipp Hug, ron minnich.

Hello Jason Nien, Martin Roth, Philipp Hug, ron minnich,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/81421?usp=email

to look at the new patch set (#2).

Change subject: src: Add missing SPDX license headers
......................................................................

src: Add missing SPDX license headers

Other files in the commits that added these files were licensed under
GPL-2.0-only, and the project as a whole is GPL-2.0-only, so use that
as the license.

Change-Id: I6c1a7ba582f61f98069ebf3857a8b5bdc8588c3e
Signed-off-by: Nicholas Chin 
---
M src/mainboard/google/myst/variants/baseboard/include/baseboard/port_descriptors.h
M src/mainboard/google/skyrim/variants/baseboard/include/baseboard/port_descriptors.h
M src/soc/sifive/fu740/include/soc/gpio.h
3 files changed, 6 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/21/81421/2