drm/nouveau/fb/ramnv50: GDDR3 script for NVA0

This looks surprisingly similar to scripts on earlier cards as well
but they don't seem to work just yet. That... and I don't have any, which
makes it a tough job to reverse engineer.

Signed-off-by: Roy Spliet <rspliet@eclipso.eu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>