wl->vif should be cleared on remove_interface()
(rather than on stop()) even when only a single
vif is supported, because during vif mode change
stop() might not get called (e.g. because of
monitor interface existence)
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>