OPENFLOW-1.1+: OFPCML_NO_BUFFER is effectively already implemented.

OpenFlow 1.2 and later define a value of 65535 (OFPCML_NO_BUFFER) for
the max_len field in an output action to mean that the switch should send
the entire packet without buffering it.  Open vSwitch never buffers packets
sent via an output action, so it trivially satisfies this requirement.

Signed-off-by: Ben Pfaff <blp@nicira.com>