hostap: Fix memory leak

The control interface is initialized on every interface add but only
de-initialized on WPA supplicant termination. This leaks all cleanups in
the control interface dei-init.

Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>
Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>