WEXT: Fixed re-initialization of removed and re-inserted interface

WEXT: Fixed re-initialization of removed and re-inserted interface

Network device ifindex will change when the interface is re-inserted.
driver_wext.c will need to accept netlink events from "unknown" (based on
ifindex) interfaces when a previously used card was removed earlier. If the
previously removed interface is added back, the driver_wext data need to be
updated to match with the new ifindex value. In addition, the initial setup
tasks for the card (set interface up, update ifindex, set mode, etc.) from
wpa_driver_wext_init() need to be run again.