LRO can play fast and loose with the packets that it merges, which
isn't very polite when you are bridging packets for other operating
systems. This disables LRO on any underlying devices that are added
to the datapath, which is the same as what the bridge does.
Note that this does not disable GRO, which has a more strict set of
rules about what is merged and is therefore safe for bridging. Both
are typically done in software anyways.
