[Nouveau] gk104: disable display underflow reporting

[Andy Ritger]

Hi Nouveau developers,

We've posted a short document about disabling display underflow reporting
on GK104, which is needed due to an incorrect setting in some production
GK104 VBIOSes:

ftp://download.nvidia.com/open-gpu-doc/gk104-disable-underflow-reporting/1/gk104-disable-underflow-reporting.txt

Thanks,
- Andy