NetUtils: add netlink msg to scan_netdevs return

The list returned by the scan_netdevs function will now also contain the
netlink message describing the device this will be used later when
creating the slave local device database.

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>