Staging: vt665x: depend on WIRELESS_EXT

Make vt665x depended on WIRELESS_EXT and remove remain ifdef's

Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>