dt-bindings: arm: mediatek: add bpi-r4 2g5 phy variant

dt-bindings: arm: mediatek: add bpi-r4 2g5 phy variant

Add new compatible for Bananapi R4 with 2.5G phy.
Base board is compatible with existing BPI-R4 only 1 SFP is replaced
by RJ45 port and use mt7988 internal phy.

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250422132438.15735-2-linux@fw-web.de
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>