phy: phy-mt65xx-usb3: increase LFPS filter threshold

Increase LFPS filter threshold to avoid some fake remote wakeup
signal which cause U3 link fail and link to U2 only at about
0.01% probability.

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