mmc: mediatek: add support for MT7986 SoC

Adding mt7986 own characteristics and of_device_id to have support
of MT7986 SoC.

Signed-off-by: Sam Shih <sam.shih@mediatek.com>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20221025132953.81286-7-linux@fw-web.de


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