Fix handler_datapath_leave()
Fix handler_datapath_leave()

This function needed to call register_ports() from self.

Ryu-RFProxy has now been tested with Ryu 3.4 and OVS 2.0.

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@wand.net.nz>

KitL/ryu-rfproxy