Bluetooth: hci_event: Fix setting DISCOVERY_FINDING for passive scanning

DISCOVERY_FINDING shall only be set for active scanning as passive
scanning is not meant to generate MGMT Device Found events causing
discovering state to go out of sync since userspace would believe it
is discovering when in fact it is just passive scanning.

Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219088


Fixes: 2e2515c1 ("Bluetooth: hci_event: Set DISCOVERY_FINDING on SCAN_ENABLED")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>