phy: phy-mt65xx-usb3: disable 100uA extraction from SS port to HS port

There will be a problem if SS port is diasbled and HS port extracts
100uA from SS port, so disable extract 100uA from SS port in the case,
when disable it, PA0_RG_USB20_INTR_EN should be set, otherwise HS port
only works on LS.

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