vfio/migration: Remove print of "Migration disabled"

Property enable_migration supports [on/off/auto].
In ON mode, error pointer is passed to errp and logged.
In OFF mode, we doesn't need to log "Migration disabled" as it's intentional.
In AUTO mode, we should only ever see errors or warnings if the device
supports migration and an error or incompatibility occurs while further
probing or configuring it. Lack of support for migration shoundn't
generate an error or warning.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/pci.c

@@ -3209,7 +3209,6 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     if (!pdev->failover_pair_id) {
         ret = vfio_migration_realize(vbasedev, errp);
         if (ret) {
-            error_report("%s: Migration disabled", vbasedev->name);
             goto out_deregister;
         }
     }