sdbus++: clean up extra error response

The property set/get and method callback functions are
suppose to return 1 or true to sdbus, otherwise the callbacks
are treated as unhandled.  Since the generated callbacks all
populate the response message correctly, the result is that the
client receives two messages but the 2nd (an error) is silently
ignored by clients because it is a duplicate message.  Clean this
up, which reduces needless activity on the dbus.

Change-Id: I39699e498b0d113ec9819670a92e44e8108c88db
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/tools/sdbusplus/templates/interface.mako.server.cpp b/tools/sdbusplus/templates/interface.mako.server.cpp
index 6f74ff5..0b71244 100644
--- a/tools/sdbusplus/templates/interface.mako.server.cpp
+++ b/tools/sdbusplus/templates/interface.mako.server.cpp
@@ -50,7 +50,7 @@
     auto o = static_cast<${classname}*>(context);
     m.append(o->${p.camelCase}());
 
-    return 0;
+    return true;
 }
 
 ${p.cppTypeName} ${classname}::${p.camelCase}(${p.cppTypeName} value)
@@ -77,7 +77,7 @@
     m.read(v);
     o->${p.camelCase}(v);
 
-    return 0;
+    return true;
 }
 
 namespace details
diff --git a/tools/sdbusplus/templates/method.mako.prototype.hpp b/tools/sdbusplus/templates/method.mako.prototype.hpp
index 090ac55..12b1574 100644
--- a/tools/sdbusplus/templates/method.mako.prototype.hpp
+++ b/tools/sdbusplus/templates/method.mako.prototype.hpp
@@ -148,7 +148,7 @@
     }
     % endfor
 
-    return 0;
+    return true;
 }
 
 namespace details