Suspend:
- Prevent the backend from being touched on TX path.
- Clear the RNDIS RX filter, and wait for RX to drain.
- Make sure that NVS see the chimney sending buffer and RXBUF disconnection, before unlink these buffers from the channel.
Resume:
- Reconfigure the RNDIS filter.
- Allow TX path to work on the backend.
- Kick start the TX eof task, in case the OACTIVE is set.
This fixes various panics, when the interface has traffic and MTU is being changed.