spapr: fix possible memory leak

get_boot_devices_list() will malloc memory, spapr_finalize_fdt
doesn't free it.
Signed-off-by: NChenliang <chenliang88@huawei.com>
Signed-off-by: NGonglei <arei.gonglei@huawei.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppc/spapr.c

@@ -783,6 +783,7 @@ static void spapr_finalize_fdt(sPAPREnvironment *spapr,
 
     cpu_physical_memory_write(fdt_addr, fdt, fdt_totalsize(fdt));
 
+    g_free(bootlist);
     g_free(fdt);
 }