iflib_device_register
ret = iflib_device_register(mif->subdev, mif, &ice_subif_sctx, &mif->subctx);
return (iflib_device_register(dev, NULL, sctx, &ctx));
int iflib_device_register(device_t dev, void *softc, if_shared_ctx_t sctx, if_ctx_t *ctxp);