ONOS-3562 Changing the flow instructions port to human readable format

Change-Id: Ia6b1a755bc400295600f4112cb3ebe676e533eb2
diff --git a/web/api/src/main/resources/definitions/Flows.json b/web/api/src/main/resources/definitions/Flows.json
index 7428d73..c803fdb 100644
--- a/web/api/src/main/resources/definitions/Flows.json
+++ b/web/api/src/main/resources/definitions/Flows.json
@@ -118,9 +118,8 @@
                       "example": "OUTPUT"
                     },
                     "port": {
-                      "type": "integer",
-                      "format": "int64",
-                      "example": -3
+                      "type": "string",
+                      "example": "CONTROLLER"
                     }
                   }
                 }