meson-gx: reset RGMII PHYs and configure TX delay

Quoted 18 lines · Martin Blumenstingl

This partially fixes the 1000Mbit/s ethernet TX throughput issues (on networks which are not affected by the EEE problem, as reported here:
[1]).
The actual problem for the TX throughput issues was that the TX delay was applied twice:
- once "accidentally" by the PHY (this was fixed with [2])
- once by the MAC because there was a hardcoded TX delay (of 2ns), this will be configurable with the changes from [0]

These are the dts changes which belong to my other series (in v2 these patches were part of the other series, upon request of the net maintainers I have split the .dts changes into their own series so we are able to take both through different trees):
"[PATCH net-next v3 0/2] stmmac: dwmac-meson8b: configurable RGMII TX delay": [0].
Thus this series depends on the ACK for the binding changes in the other series!

Quoted 2 lines

I based these changes on my other series "[PATCH v2 0/2] GXL and GXM SCPI improvements": [3]

the DT binding changes for the meson8b-dwmac driver were ACK'ed by Rob Herring, so you can proceed with this series once you applied the SCPI patches.