usb: mtu3: re-enable controller to accept LPM request after LPM resume

After the controller receives a LPM request, it will reject the LPM
request, and need software to re-enable it after LPM resume if the
controller doesn't remote wakeup from L1 automatically

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>