Bluetooth: Always request for user confirmation for Just Works

To improve security, always give the user-space daemon a chance to
accept or reject a Just Works pairing (LE). The daemon may decide to
auto-accept based on the user's intent.

Signed-off-by: Sonny Sasaka <sonnysasaka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>