Change in coreboot[master]: soc/intel/skylake: Auto-configure SerialIoDevMode UPD

[Furquan Shaikh (Code Review)]

Attention is currently required from: Angel Pons, Patrick Rudolph.
Furquan Shaikh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/55224 )

Change subject: soc/intel/skylake: Auto-configure SerialIoDevMode UPD
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Patch Set 1:

(1 comment)

File src/soc/intel/skylake/Kconfig:

https://review.coreboot.org/c/coreboot/+/55224/comment/21a41625_87fe764f 
PS1, Line 180: DERIVE_SERIALIO_CFG_FROM_DEV_STATE
Is this Kconfig required? The change looks like the direction we would want to go in for all mainboards i.e. eliminate the devicetree config and instead rely on SoC determining the correct values for the UPDs based on device state in devicetree and other configs.