How to make the device able to sleep when usb cable is connected with PC

Only if usb in suspend status, device can sleep with usb cable connected

In sleep task, it will check votes from usb, if usb does not allow to turn off TXCO, the device can not go to deep sleep.
When the usb cable connect to PC, usb task will not vote for deep sleep unless the usb core go to suspend status.

There are some scenarios that the usb core can get suspend event:
1. The host remove the usb device in device manager.
2. The host disable the driver of the usb device
3. The host go to standby mode
4. The host enable selective suspension and there is no activity on usb bus after the set timeout value.

In AMSS, the usb code can get a interrupt for suspend if the scenario happen.
please see 80-v4609-1 about enable selective suspension in Windows.