cppcheck: variable reassigned before the old value has been used

For more details, see http://nabble.documentfoundation.org/Cppcheck-redundantAssignment-gridcell-cxx-svx-module-td4095032.html

Change-Id: I9b74a819a1431f5eada727d14933133fbdf7a47f

svx/source/fmcomp/gridcell.cxx

@@ -2145,8 +2145,6 @@ namespace
                 if ( !_rxField->wasNull() )
                 {
                     _rField.SetValue( fValue );
-                    BigInt aValue = _rField.GetCorrectedValue();
-                    sValue = aValue.GetString();
                     sValue = _rField.GetText();
                 }
             }