dt-bindings: phy-mt65xx-usb: add support for new version phy

add a new compatible string for "mt2712", and move reference clock
into each port node;

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>