vfio/pci: Fix a use-after-free issue

vbasedev->name is freed wrongly which leads to garbage VFIO trace log.
Fix it by allocating a dup of vbasedev->name and then free the dup.

Fixes: 2dca1b37a760 ("vfio/pci: add support for VF token")
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/pci.c

@@ -2994,7 +2994,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         qemu_uuid_unparse(&vdev->vf_token, uuid);
         name = g_strdup_printf("%s vf_token=%s", vbasedev->name, uuid);
     } else {
-        name = vbasedev->name;
+        name = g_strdup(vbasedev->name);
     }
 
     ret = vfio_get_device(group, name, vbasedev, errp);