Change in coreboot[master]: driver/intel/fsp2_0: Allow function to run serially on all APs

[Paul Menzel (Code Review)]

Attention is currently required from: Tim Wawrzynczak, Subrata Banik, Aamir Bohra, Andrey Petrov, Patrick Rudolph.
Paul Menzel has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51085 )

Change subject: driver/intel/fsp2_0: Allow function to run serially on all APs
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Patch Set 2:

(3 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/51085/comment/d58aebca_d057f080 
PS2, Line 9: singlethread
The name seems to be `run_serial`.

https://review.coreboot.org/c/coreboot/+/51085/comment/d28c5e6b_84a72c2b 
PS2, Line 14: 
Please give some numbers, on how much time this actually saves. Concurrency can (and often does) add a lot of hard-to-debug problems.

It might be a good idea to add a commit before, adding timestamps for this port or printing the execution time using the stopwatch framework.

File src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c:

https://review.coreboot.org/c/coreboot/+/51085/comment/55735591_6768a9d6 
PS2, Line 67: run_serial
I’d prefer the opposite name `run_in_parallel`.