dt-bindings: phy-mt65xx-usb: add support for mt2701 platform

Add a new compatible string for "mt2701"

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>