Hack to get wifi to work after connman has crashed

Normally, after connman crashes and gets restarted by systemd, wifi connectivity stops working until the phone is rebooted (or connman is shut down gracefully and restarted with systemctl stop/start but users don't know and don't want to know how to do that).

It appears that wpa_supplicant interfaces must be removed prior to bringing wifi interfaces down (which is something connman does every time at startup); otherwise supplicant gets into INTERFACE_DISABLED state and nothing works. During the graceful shutdown, supplicant interface gets removed; if connman suddenly dies, it stays alive.

This hack makes sure that interfaces are removed before cleanup_devices() is called, thus allowing wifi connectivity to recover from the connman crash.