ovs-ofctl: Use 65535 instead of 0 for OFPP_CONTROLLER max_len.

OpenFlow 0.9 will change the interpretation of a max_len of 0 in an
OFPP_CONTROLLER output action from "send entire packet" to "send 0 bytes
of packet", but ovs-ofctl documents that specifying no argument or "ALL"
as the argument to a CONTROLLER output action sends the whole packet, so
we need to make that happen.