Bluetooth: Mgmt Device Found Event

We only want to send Mgmt Device Found Events if we are running the
Device Discovery procedure (started by the MGMT Start Discovery
Command). Inquiry or LE scanning triggered by HCI raw interface (e.g.
hcitool) or kernel internals should not send Mgmt Device Found Events.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Acked-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>