cppcheck: knownConditionTrueFalse 'bRet' is always false

regression of commit 52863266
Date:   Thu Feb 9 08:52:13 2017 +0200
    convert ErrCode to strong typedef

Change-Id: I5ce2b7d38c8d71ec40cc8de7c13e8aec637476b7
Reviewed-on: https://gerrit.libreoffice.org/42139Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

reportdesign/source/filter/xml/xmlfilter.cxx

@@ -559,8 +559,7 @@ bool ORptFilter::implImport( const Sequence< PropertyValue >& rDescriptor )
         }
 
 
-        bRet = false;
-        nRet = ERRCODE_NONE;
+        bRet = nRet == ERRCODE_NONE;
 
         if ( bRet )
         {