Fix a boot-time panic in qcom_mdio_ipq4018 due to a missing bus function
and hook the file up to the build so that it will not rot away.
Test booted on an ipq807x in 2022.
X-Differential Revision: extracted from D37882
The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.
Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix
This adds support for the IPQ4018/IPQ4019 MDIO bus. This is used to
talk to external PHYs and switches. (There's an internal switch
in the IPQ4018/IPQ4019 as well, but it's accessible via MMIO/AXI.)
Differential Revision: https://reviews.freebsd.org/D34110
Reviewed by: manu
