net: stmmac: dwmac-renesas-gbeth: Use OF data for configuration

net: stmmac: dwmac-renesas-gbeth: Use OF data for configuration

Prepare for adding RZ/T2H SoC support by making the driver configuration
selectable via OF match data. While the RZ/V2H(P) and RZ/T2H use the same
version of the Synopsys DesignWare MAC (version 5.20), the hardware is
synthesized with different options. To accommodate these differences,
introduce a struct holding per-SoC configuration such as clock list,
number of clocks, TX clock rate control, and STMMAC flags, and retrieve
it from the device tree match entry during probe.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://patch.msgid.link/20250908105901.3198975-3-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>