1. Fix WiFi scan leads to poor performance of Bluetooth.
2. Improve WiFi connect success ratio when coexist with Bluetooth.
3. Check if WiFi is still connected when CSA or beacon timeout happen.
4. add coex pre init
1. Fix high beacon and broadcast packets loss ratio of WiFi to make
MDNS test pass.
2. Improve stability of WiFi performance with a little
sacrifice of throughput.
3. Improve BLE advertising and connection performance with dynamic
priority. It sacrifices a little WiFi throughput, but achieves balance
between WiFi and Bluetooth.