drm/nouveau/gr/gf100-: virtualise alpha_beta_tables + improve algorithms

drm/nouveau/gr/gf100-: virtualise alpha_beta_tables + improve algorithms

I haven't yet been able to find a fully programatic way of calculating the
same mapping as NVIDIA for GF100-GF119, so the algorithm partially depends
on data tables for specific configurations.

I couldn't find traces for every possibility, so the algorithm will switch
to a mapping similar to what GK104-GM10x use if it encounters one.  We did
the wrong thing before anyway, so shouldn't matter too much.

The algorithm used in the GK104 implementation was ported from NVGPU.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>