Fix IP address cleanup on network disconnect

We used to bring down the interface on network disconnect
which would in turn clean up all the IP addresses.

The interface bringup/shutdown is now handled by wpa_supplicant.
Add netd interface for clearing all IP addresses

Bug: 4676254
Change-Id: I7e24c0ab2e4a412b8d61e9c33ce028966913aaf6
3 files changed