[coreboot-gerrit] Change in coreboot[master]: timestamp: Add new helper functions

[Angel Pons (Code Review)]

Attention is currently required from: Bora Guvendik, Furquan Shaikh, Selma Bensaid, Tim Wawrzynczak, Julius Werner, Subrata Banik, Aaron Durbin.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51445 )

Change subject: timestamp: Add new helper functions
......................................................................

Patch Set 8:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/51445/comment/1b15d19c_2d378741 
PS3, Line 7: Add helper fucntions
> Yeah, I don't really know what you did there to be honest... […]

I wouldn't move the base timestamp, but instead add these timestamps with a negative delta. It makes sense, since these events happened before the CPU has started executing code from the reset vector.