dt-bindings: mediatek: Add bindings for MT6795 M4U

Add bindings for the MediaTek Helio X10 (MT6795) IOMMU/M4U.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220913151148.412312-2-angelogioacchino.delregno@collabora.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>