drm/nouveau/device: return error for unknown chipsets

Previously the code relied on device->pri to be NULL and to fail probing
later. We really should just return an error inside nvkm_device_ctor for
unsupported GPUs.

Fixes: 24d5ff40 ("drm/nouveau/device: rework mmio mapping code to get rid of second map")
Signed-off-by: NKarol Herbst <kherbst@redhat.com>
Cc: dann frazier <dann.frazier@canonical.com>
Cc: dri-devel <dri-devel@lists.freedesktop.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: NJeremy Cline <jcline@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201006220528.13925-1-kherbst@redhat.com

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

@@ -3149,6 +3149,7 @@ nvkm_device_ctor(const struct nvkm_device_func *func,
 		case 0x168: device->chip = &nv168_chipset; break;
 		default:
 			nvdev_error(device, "unknown chipset (%08x)\n", boot0);
+			ret = -ENODEV;
 			goto done;
 		}