[coreboot] Howto enable AMD Cool'n'Quiet support

[Rudolf Marek]

Hi,

> I checked coreboot.rom-file and my vendor BIOS for that but can't find it.

The coreboot provides the _PSS ACPI objects and not that PSB table. I guess you 
miss the _PSS objects for some reason.

> Did I miss to enable something in make menuconfig? Can someone give me a hint 
> how to find the missing blob.

If your CPU is pre rev F family 0xf, the _PSS object is generated using a 
hardcoded table. Perhaps your CPU is missing there. See powernow_acpi.c
coreboot should also complain if the CPU is missing there:

"Unknown CPU, please update the powernow_acpi.c"

Thanks
Rudolf