Update wpa_supplicant to version 2.0 and bring in improvements.

* Updated to version 2.0 of vendor code.
* Reliability improvements in controlling the underlying devices.
* Implement leaving networks.
* Better timeout handling.
* Usability enhancements like cancel on escape, ok button being the
  default and the password field having focus on start.
* Storing of the password using BKeyStore.
Implement leaving networks on the net_server side.

We always try to reach the wpa_supplicant first. If it isn't running
we check if this might have been a network we've connected directly
and then just disassociate using an MLME disassociation request.