drm/nouveau/clk: implement stub clock subdev

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/Makefile b/drivers/gpu/drm/nouveau/Makefile
index 40ce4e1..2964d71 100644
--- a/drivers/gpu/drm/nouveau/Makefile
+++ b/drivers/gpu/drm/nouveau/Makefile
@@ -23,6 +23,11 @@
 nouveau-y += core/subdev/bios/dcb.o
 nouveau-y += core/subdev/bios/gpio.o
 nouveau-y += core/subdev/bios/i2c.o
+nouveau-y += core/subdev/clock/nv04.o
+nouveau-y += core/subdev/clock/nv40.o
+nouveau-y += core/subdev/clock/nv50.o
+nouveau-y += core/subdev/clock/nva3.o
+nouveau-y += core/subdev/clock/nvc0.o
 nouveau-y += core/subdev/device/base.o
 nouveau-y += core/subdev/device/nv04.o
 nouveau-y += core/subdev/device/nv10.o