drm/nouveau/platform: add GPU speedo information to nouveau platform

For GK20A we need the GPU speedo value to calculate voltage levels.

Signed-off-by: Vince Hsu <vinceh@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --cc drivers/gpu/drm/nouveau/nouveau_platform.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/nouveau_platform.h
Simple merge