Change in coreboot[master]: mb/prodrive/hermes: Fix PCIe ClkSrc configuration

[Michael Niewöhner (Code Review)]

Attention is currently required from: Patrick Rudolph, Christian Walter, Angel Pons.
Michael Niewöhner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/58065 )

Change subject: mb/prodrive/hermes: Fix PCIe ClkSrc configuration
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Patch Set 2:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/58065/comment/86efbaec_6dbce2dd 
PS2, Line 10: Apparently, FSP does not turn off unused PCIe clock sources when using
> I cannot find that code in FSP, where does it check for SPS?

Same here; also, this doesn't make *any* sense to me tbh o.O

What I don't get: How does fixing detection of BMC and others relate to turning off unused clocks?
For BMC `PCIE_CLK_NOTUSED` was set, so it's force-disabled by FSP. `PCIE_CLK_FREE` force-enables the clock ("free-running").