arm64: dts: mt8173: remove "mediatek, mt8135-mmc" from mmc nodes

devicetree bindings has been updated to support multi-platforms,
so that each platform has its owns compatible name.
And, this compatible name may used in driver to distinguish with
other platform.

Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Tested-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>