PR0 needs porting of upstream patch to downstream forks

[tlaurion]

@nestire @daringer @jans23: Removing ns50 lock_chip because I cannot test. Simple to add, just revert next commit in a PR after testing it and I will merge.

@JonathonHall-Purism patch needed on coreboot purism fork

All downstream coreboot forks: Please refer to #1818 for how to enable PR0 from board config and config/coreboot* config files if not using upstream, adapt https://review.coreboot.org/c/coreboot/+/85278 and create PR upstream (under https://github.com/linuxboot/heads) prior of #1821 if you intend to have the feature before freeze for your platforms.

originally posted at #1818 (comment)

Also see #1659