David Hendricks firstname.lastname@example.org once said:
IANAL, but from what I understand it's usually a good idea to avoid mucking with legalese as to avoid unintended consequences of how licenses are enforced, particularly with regard to international treaties pertaining to IP and copyrighted works.
The Go project uses short license headers so it must have already been vetted by Google's team of lawyers.
Also, there are a few distinct free software licenses used in coreboot so I'd hate to add to the confusion. Keeping the licenses in their canonical form and applying them to ever file ensures that coreboot gets all the proper legal protections.
Here's an example of how code with a different license is handled in the Go project: