hw/vhost-user-scsi|blk: set `supports_config` flag correctly

hw/vhost-user-scsi|blk: set `supports_config` flag correctly

Currently vhost-user-scsi driver doesn't allow to change
the configuration space of virtio_scsi, while vhost-user-blk
support that, so here we set the flag in vhost-user-blk driver
and unset it in vhost-user-scsi.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Message-Id: <20220525125540.50979-2-changpeng.liu@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>