EXA support for nv, new version

[Lars Knoll]

Hi, 

I've updated the EXA support for the open source nv driver. 

I fixed a few bugs in the driver for HW older than NV40, and followed Bens 
suggestion not to mmap agp memory through the agpgart module. 

This required me to write a minimalistic drm module for nv. You can find up to 
date patches here:

http://trolls.troll.no/lars/patches/nv.diff
http://trolls.troll.no/lars/patches/drm.diff

Cheers,
Lars