dt-bindings: mmc: mtk-sd: Document compatibles that need two register ranges

Besides the MT8183's MMC controller and all its compatible derivatives,
the recently added MT7986 and MT8196 also require two register ranges.
This is based on the actual device trees.

Properly enforce this in the binding.

Fixes: 4a8bd2b0 ("dt-bindings: mmc: mtk-sd: Add mt7988 SoC")
Fixes: 58927c9d ("dt-bindings: mmc: mtk-sd: Add support for MT8196")
Cc: Frank Wunderlich <frank-w@public-files.de>
Cc: Andy-ld Lu <andy-ld.lu@mediatek.com>
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Message-ID: <20241210073212.3917912-2-wenst@chromium.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>