drm/nouveau/devinit/gf100: make the force-post condition more obvious

And also more generic, so it can be used on newer chipsets.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/devinit/gf100.c

@@ -95,7 +95,9 @@ gf100_devinit_ctor(struct nvkm_object *parent, struct nvkm_object *engine,
 		   struct nvkm_oclass *oclass, void *data, u32 size,
 		   struct nvkm_object **pobject)
 {
+	struct nvkm_devinit_impl *impl = (void *)oclass;
 	struct nv50_devinit_priv *priv;
+	u64 disable;
 	int ret;
 
 	ret = nvkm_devinit_create(parent, engine, oclass, &priv);
@@ -103,7 +105,8 @@ gf100_devinit_ctor(struct nvkm_object *parent, struct nvkm_object *engine,
 	if (ret)
 		return ret;
 
-	if (nv_rd32(priv, 0x022500) & 0x00000001)
+	disable = impl->disable(&priv->base);
+	if (disable & (1ULL << NVDEV_ENGINE_DISP))
 		priv->base.post = true;
 
 	return 0;