dt-bindings: memory: mediatek: Add a common memory header file

Put all the macros about smi larb/port togethers.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-3-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>