wlcore: flush before stopping AP

Make sure the deauth bcast gets sent

[Make sure we are AP as well before the flush - Arik]

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>