Bluetooth: Provide flags parameter direct to mgmt_device_found

Providing the flags parameter directly to mgmt_device_found function
makes the core simpler and more readable. With this it becomes a lot
easier to add new flags in the future.

This also changes hci_inquiry_cache_update to just return that flags
needed for mgmt_device_found since that is its only use for the two
return parameters anyway.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>