Refine the interface info returned by hwinfo.
We do NOT return interfaces: - with obviously hacky and fake addresses: '000000xxxxxx' - when they are management (role == 'mngmnt') interfaces. Currently there is no OS visible HW for these, the corresponding MACs are just used by the management HW. - for Infiniband (guid != NULL) interfaces. We need support on the client side before we start sending those over.