arm64: dts: mediatek: Fix "mediatek,merge-mute" and "mediatek,merge-fifo-en" types

"mediatek,merge-mute" and "mediatek,merge-fifo-en" properties are defined
and used as boolean properties which in DT have no value.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230830195650.704737-1-robh@kernel.org


Signed-off-by: Arnd Bergmann <arnd@arndb.de>