dt-bindings: phy: convert phy-mtk-tphy.txt to YAML schema

Convert phy-mtk-tphy.txt to YAML schema mediatek,tphy.yaml

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201225075258.33352-4-chunfeng.yun@mediatek.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>