[VOL-936] add changes for onu distance proto

Change-Id: Iedc44ff0c1c26a7d3623d4b7d96bb2d425d5d24f
diff --git a/protos/voltha_protos/voltha.proto b/protos/voltha_protos/voltha.proto
index b8edd31..e6d9fdd 100644
--- a/protos/voltha_protos/voltha.proto
+++ b/protos/voltha_protos/voltha.proto
@@ -597,6 +597,11 @@
             body: "*"
         };
     }
+    rpc GetExtValue(common.ValueSpecifier) returns(common.ReturnValues) {
+        option (google.api.http) = {
+            get: "/api/v1/GetExtValue"
+        };
+    }
 
     // omci start and stop cli implementation
     rpc StartOmciTestAction(OmciTestRequest) returns(TestResponse) {