property_return was free'd before and in the case the conditional is true,
the call to XcmsGetProperty failed which means that property_return wasn't
set so there is no need to free it again.

Double free of pointer "property_return" in call to "free"
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Erkki Seppälä <erkki.seppala@vincit.fi>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan-de-oliveira@nokia.com>
Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>