arm64: dts: mediatek: Add spherion-rev4

Add a devicetree for rev4 of Spherion. It uses the rt5682s audio codec
instead of the rt5682 used in the previous revision.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230721201705.387426-6-nfraprado@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>