[L] Change in coreboot[master]: mb/ibm: Add IBM SBP1

[Paul Menzel (Code Review)]

Attention is currently required from: Patrick Rudolph, David Hendricks, Shuo Liu, Nill Ge.

Paul Menzel has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/73392 )

Change subject: mb/ibm: Add IBM SBP1
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Patch Set 9: Code-Review+1

(3 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/73392/comment/c880171b_3261319c 
PS9, Line 7: Add IBM SBP1
Maybe more specific:
> Add 4 SPR sockets server board IBM SBP1

https://review.coreboot.org/c/coreboot/+/73392/comment/73b722d3_c25a46e8 
PS9, Line 26: Linux
What Linux kernel did you test with?

https://review.coreboot.org/c/coreboot/+/73392/comment/1278f124_c9c98929 
PS9, Line 29: 
Is `dmesg --level crit,alert,err,warn` empty?