[coreboot] SB600 HDA can't find codec fix

[Dan Lykowski]

These changes allow the SB600 HDA to detect the codec correctly. I haven't had time to test the sound output, but Linux now detects it correctly. I don't see why it wouldn't work. Feel free to give it a whirl and let me know if more work is needed.

Signed-off-by: Dan Lykowski