[tests] agent_sflow_test set ovsdb port to 6400
[tests] agent_sflow_test set ovsdb port to 6400

ovsdb must be the same as define in ovsdb-server commandline.

fdebonneval/skydive,fdebonneval/skydive,skydive-project/skydive,safchain/skydive,lebauce/skydive,redhat-cip/skydive,safchain/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,safchain/skydive,redhat-cip/skydive,safchain/skydive,skydive-project/skydive,safchain/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive,fdebonneval/skydive,skydive-project/skydive,skydive-project/skydive,safchain/skydive,lebauce/skydive,redhat-cip/skydive,safchain/skydive,safchain/skydive