arm64: dts: mediatek: mt8188: Add ethernet node

Describe the ethernet present on the MT8188.

[Cleaned up to pass dtbs_check, follow DTS style guidelines, removed
hardcoded mac address and split between mt8188 and genio700 commits,
and addressed further feedback from the mailing list]

Signed-off-by: Jianguo Zhang <jianguo.zhang@mediatek.com>
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Signed-off-by: Hsuan-Yu Lin <shane.lin@canonical.com>
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20241018-genio700-eth-v2-1-f3c73b85507b@collabora.com


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>