Comment # 35 on bug 1009674 from Takashi Iwai

I don't see a clear reason why it triggers a panic yet, but I think I found the
missing piece in the previous patch.  It's accessing the pp_ctrl_reg that isn't
initialized for VLV/CHV but only for BXT.

Below is the revised patch.  Could you give it a try?  I'll update the kernel
package in my repo, too.