Bluetooth: mgmt: Fix limited discoverable off timeout

LIMITED_DISCOVERABLE flag is not reset from Class of Device and
advertisement on limited discoverable timeout. This prevents to pass PTS
test GAP/DISC/LIMM/BV-02-C

Calling set_discoverable_sync as when the limited discovery is set
correctly update the Class of Device and advertisement.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>