Fix use after free in vfio_migration_probe

Fixes Coverity issue:
CID 1436126:  Memory - illegal accesses  (USE_AFTER_FREE)

Fixes: a9e271ec ("vfio: Add migration region initialization and finalize function")
Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: David Edmondson <dme@dme.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/vfio/migration.c

@@ -897,8 +897,8 @@ int vfio_migration_probe(VFIODevice *vbasedev, Error **errp)
         goto add_blocker;
     }
 
-    g_free(info);
     trace_vfio_migration_probe(vbasedev->name, info->index);
+    g_free(info);
     return 0;
 
 add_blocker: