phy: phy-mt65xx-usb3: add PCIe PHY support

This patch adds PCIe PHY setting part.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>