Change in coreboot[master]: skylake DDR4 boards: Set `CaVrefConfig` to 2

[Nico Huber (Code Review)]

Attention is currently required from: Frans Hendriks, Matt DeVillier, Angel Pons, Arthur Heymans, Michael Niewöhner, Patrick Rudolph, Wim Vervoorn.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57262 )

Change subject: skylake DDR4 boards: Set `CaVrefConfig` to 2
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Patch Set 3:

(1 comment)

File src/mainboard/kontron/bsl6/romstage.c:

https://review.coreboot.org/c/coreboot/+/57262/comment/e8689ada_2633ae40 
PS3, Line 40: 	memory_params->CaVrefConfig = 2;
Hmmm, I was much surprised to see that we didn't query Kontron about this
(we asked for other parameters during early bring-up). So, I just don't
know what is right.

We can at least test this setting, though. Felix, the 1 HU box.