dt-bindings: memory: mediatek: Convert SMI to DT schema

Convert MediaTek SMI to DT schema.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201103054200.21386-2-yong.wu@mediatek.com


Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>