Rather than using the DEVICE_IDENTIFY method, let's have other ofwbus-using platforms add ofwbus0 explicitly in nexus, like arm64. This gives them the same flexibility, e.g. if riscv starts supporting ACPI, and cleans up the #ifdefs. We were doing this already on riscv, but adjust the 'order' parameters. Reviewed by: andrew, jhb MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D38492