drm/nouveau/disp: allow user direct access to channel control registers

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

diff --cc drivers/gpu/drm/nouveau/core/engine/disp/nv50.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/disp/nv50.h
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/disp/nvd0.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/nv50_display.c
Simple merge