spapr: Fixes a leak in CAS

Add a missing g_free(fdt) if the resulting tree is bigger
than the space allocated by SLOF.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>

hw/ppc/spapr.c

@@ -1026,6 +1026,7 @@ int spapr_h_cas_compose_response(SpaprMachineState *spapr,
     _FDT((fdt_pack(fdt)));
 
     if (fdt_totalsize(fdt) + sizeof(hdr) > size) {
+        g_free(fdt);
         trace_spapr_cas_failed(size);
         return -1;
     }