drm/nouveau/clk: implement stub clock subdev

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/core/subdev/device/nv04.c b/drivers/gpu/drm/nouveau/core/subdev/device/nv04.c
index e0ebbe1..e24e74b 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/device/nv04.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/device/nv04.c
@@ -25,6 +25,7 @@
 #include <subdev/device.h>
 #include <subdev/bios.h>
 #include <subdev/i2c.h>
+#include <subdev/clock.h>
 
 int
 nv04_identify(struct nouveau_device *device)
@@ -33,10 +34,12 @@
 	case 0x04:
 		device->oclass[NVDEV_SUBDEV_VBIOS  ] = &nouveau_bios_oclass;
 		device->oclass[NVDEV_SUBDEV_I2C    ] = &nouveau_i2c_oclass;
+		device->oclass[NVDEV_SUBDEV_CLOCK  ] = &nv04_clock_oclass;
 		break;
 	case 0x05:
 		device->oclass[NVDEV_SUBDEV_VBIOS  ] = &nouveau_bios_oclass;
 		device->oclass[NVDEV_SUBDEV_I2C    ] = &nouveau_i2c_oclass;
+		device->oclass[NVDEV_SUBDEV_CLOCK  ] = &nv04_clock_oclass;
 		break;
 	default:
 		nv_fatal(device, "unknown RIVA chipset\n");