[L] Change in coreboot[main]: mb/dell: Add OptiPlex 7020/9020 port

[Leah Rowe (Code Review)]

Attention is currently required from: Arthur Heymans, Michael Büchler, Máté Kukri, Nico Huber, Paul Menzel, ilikenwf, nat ✨.

Leah Rowe has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/55232?usp=email )

Change subject: mb/dell: Add OptiPlex 7020/9020 port
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Patch Set 33:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/55232/comment/65782876_8e1923cc :
PS33, Line 11: PWN
> also, you say EC which i assume means embedded controller but this isn't a laptop, isn't it the supe […]

so long as the iommu issue is also mentioned in commit msg (and maybe tell how to remove it when building), i'm happy for this to merge if the coreboot gods accepts it - the iommu bug and pwm bug can both be mitigated for the time being, and documentation can be added later to explain how.