dt-bindings: mmc: Add compatible for MT6795 Helio X10 SoC

Add a compatible string for the MT6795 SoC's mtk-sd mmc controllers.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220729104441.39177-3-angelogioacchino.delregno@collabora.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>