wl12xx:support ap a2dp coex

Add functionality to support AP A2DP co-existence:

1. Add configuration for enable/disable of CTS protection in AP mode
2. Add indication for completion of connection establishment in ap
   mode. This is used by the firmware to change coex parameters
   when a station is in the process and connecting to the ap and
   change them back after the connection has been established.

Signed-off-by: Eyal Reizer <eyalr@ti.com>