Bluetooth: Fix hci_create_le_conn()

When a LE device we want automatically connect to is found during the
device discovery procedure, we create the connection. Since some LE
controllers don't support scanning and initiating state combination,
the scanning will be disabled therefore we should set the discovery
state to DISCOVERY_STOPPED

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Auto connection and power off/on

If hdev is closed (e.g. Mgmt power off command, RFKILL or controller is
reset), the established connections are dropped and no Disconnection
Complete Event is sent to host. This way, the background scan is not
triggered when devices configured with BT_AUTO_CONN_ALWAYS option
disconnect. To fix this issue, before dropping the LE connections, we
trigger the background scan for each connected device that requires
BT_AUTO_CONN_ALWAYS auto connection.

Moreover, once the adapter is powered on, we should start the background
scan if we have triggers registered. This way, we keep the background
scan running after a power off and power on sequence.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>