arm64: dts: mediatek: Update the node name of SCP rpmsg subnode

Align the node name with the definition in SCP bindings.

Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20230901080935.14571-3-tinghan.shen@mediatek.com


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>