[coreboot-gerrit] Change in coreboot[master]: [WIP,RFC] Clean up spinlocks

[Raul Rangel (Code Review)]

Attention is currently required from: Jason Glenesk, Marshall Dawson, Tim Wawrzynczak, Julius Werner, Kyösti Mälkki, Karthikeyan Ramasubramanian, Felix Held.
Raul Rangel has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/59094 )

Change subject: [WIP,RFC] Clean up spinlocks
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Patch Set 2: Code-Review+1

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/59094/comment/94297803_d3583d28 
PS2, Line 11: TBD: Breaks romstage co-operative threading, since those
            : need implementation of spin_lock() that is not a spinlock.
It's already broken.

https://review.coreboot.org/c/coreboot/+/59094/comment/2e04f4c1_1d88b875 
PS2, Line 14: IMO commit a98d302fe9 x86/smp/spinlock: Disable thread coop when taking spinlock
            : is wrong and should be reverted too.
I'm fine doing that if we can come up with another way of preventing udelay from calling `thread_yield_microseconds` while in a critical section.