drm/gm204/devinit: initial implementation

Starting from GM204, certain registers are no longer accessible by the host
(or unsigned PMU firmware).

This commit implements devinit on PMU, using a signed microcode image, and
devinit data, from the VBIOS.

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

diff --cc drivers/gpu/drm/nouveau/Makefile
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/include/subdev/devinit.h
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/devinit/gm107.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/devinit/gm204.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/devinit/nv50.h
Simple merge