Fix for vblank on nvc0

[Maarten Lankhorst]

Op 06-11-12 15:48, Kelly Doran schreef:
> The vblank on nvc0 was not working correctly and would freeze X, I managed
> to track it down and fix it with some help from m.b.lankhorst, see
> https://bugs.freedesktop.org/show_bug.cgi?id=56692 for details.
>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at canonical.com>

I recommended the bar flush since nvd0 does as well, and there might be a small race
otherwise.

Can this still get in before final 3.7 release?

~Maarten