dt-bindings: memory: mediatek: Add mt8192 support

Add mt8192 smi support in the bindings.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201103054200.21386-3-yong.wu@mediatek.com


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