PFW: avoid warning in SubsystemObject

BZ: 103961

In current implementation of PFW, if a subsytem does not implement
full interface of SubsystemObject, a warning message is logged.

The purpose of this patch is to change the default behaviour and
do not more log a warning.

Change-Id: I51bc61a418956553d3c880aafa622ca6c2f68520
Signed-off-by: Andrei V. FOMITCHEV <andreix.fomitchev@intel.com>
Reviewed-on: http://android.intel.com:8080/106320
Reviewed-by: Barthes, FabienX <fabienx.barthes@intel.com>
Tested-by: Dixon, CharlesX <charlesx.dixon@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
diff --git a/parameter/SubsystemObject.cpp b/parameter/SubsystemObject.cpp
index d79789b..c778baf 100644
--- a/parameter/SubsystemObject.cpp
+++ b/parameter/SubsystemObject.cpp
@@ -139,11 +139,12 @@
     return false;
 }
 
-bool CSubsystemObject::receiveFromHW(string& strError)
+bool CSubsystemObject::receiveFromHW(string& )
 {
-    strError = "Receive from HW interface not implemented at subsystsem level!";
+    // Back synchronization is not supported at subsystem level.
+    // Rely on blackboard content
 
-    return false;
+    return true;
 }
 
 // Fall back HW access