drm/nouveau/device: add direct pointer to struct device

A future commit will hide the platform/pci specifics from nvkm_device,
but it's still very useful in a lot of places to have access to the
Linux device struct.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvkm/core/device.h

@@ -9,6 +9,7 @@ struct nvkm_device {
 
 	struct pci_dev *pdev;
 	struct platform_device *platformdev;
+	struct device *dev;
 	u64 handle;
 
 	struct nvkm_event event;

drivers/gpu/drm/nouveau/nvkm/engine/device/base.c

@@ -764,9 +764,11 @@ nvkm_device_create_(void *dev, enum nv_bus_type type, u64 name,
 	switch (type) {
 	case NVKM_BUS_PCI:
 		device->pdev = dev;
+		device->dev = &device->pdev->dev;
 		break;
 	case NVKM_BUS_PLATFORM:
 		device->platformdev = dev;
+		device->dev = &device->platformdev->dev;
 		break;
 	}
 	device->handle = name;