rpc: Fix name of member in remote_protocol-structs

Commit 7a99b0ab adds a new RPC struct
but one of the members has different names in remote_protocol.x and
remote_protocol-struct breaking make check.

src/remote_protocol-structs

@@ -981,7 +981,7 @@ struct remote_network_update_args {
         remote_nonnull_network     net;
         u_int                      command;
         u_int                      section;
-        int                        index;
+        int                        parentIndex;
         remote_nonnull_string      xml;
         u_int                      flags;
 };