Merge branch 'add-ethernet-mac-support-for-spacemit-k1'

Vivian Wang says:

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Add Ethernet MAC support for SpacemiT K1

SpacemiT K1 has two gigabit Ethernet MACs with RGMII and RMII support.
Add devicetree bindings, driver, and DTS for it.

Tested primarily on BananaPi BPI-F3. Basic TX/RX functionality also
tested on Milk-V Jupiter.

I would like to note that even though some bit field names superficially
resemble that of DesignWare MAC, all other differences point to it in
fact being a custom design.

Based on SpacemiT drivers [1]. These patches are also available at:

https://github.com/dramforever/linux/tree/k1/ethernet/v12

[1]: https://github.com/spacemit-com/linux-k1x
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Link: https://patch.msgid.link/20250914-net-k1-emac-v12-0-65b31b398f44@iscas.ac.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>