drm/nouveau/gpio: use base constructor for all implementations

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

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

diff --cc drivers/gpu/drm/nouveau/core/subdev/gpio/base.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/gpio/nv10.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/gpio/nv50.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/gpio/nv92.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/gpio/nvd0.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/gpio/nve0.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/core/subdev/gpio/priv.h
Simple merge