Transactional modification. OpenFlow 1.4 requires to support
flow_mods and port_mods in a bundle if bundle is supported.
(Not related to OVS's 'ofbundle' stuff.)
+ Implemented as an OpenFlow 1.4 feature. Only flow_mods and
+ port_mods are supported in a bundle. If the bundle includes port
+ mods, it may not specify the OFPBF_ATOMIC flag. Nevertheless,
+ port mods and flow mods in a bundle are always applied in order
+ and consecutive flow mods between port mods are made available to
+ lookups atomically.
[EXT-230]
[optional for OF1.4+]