drm/g94-/disp: add method to power-off dp lanes

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

diff --cc drivers/gpu/drm/nouveau/core/engine/disp/nv94.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/engine/disp/nva3.c
Simple merge

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

diff --cc drivers/gpu/drm/nouveau/core/engine/disp/sornv50.c
Simple merge

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