vfio/ccw: Don't initialize HOST_IOMMU_DEVICE with mdev

mdevs aren't "physical" devices and when asking for backing IOMMU info,
it fails the entire provisioning of the guest. Fix that by setting
vbasedev->mdev true so skipping HostIOMMUDevice initialization in the
presence of mdevs.

Fixes: 9305895201 ("vfio/iommufd: Implement HostIOMMUDeviceClass::realize() handler")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

hw/vfio/ccw.c

@@ -675,6 +675,9 @@ static void vfio_ccw_instance_init(Object *obj)
     VFIOCCWDevice *vcdev = VFIO_CCW(obj);
     VFIODevice *vbasedev = &vcdev->vdev;
 
+    /* CCW device is mdev type device */
+    vbasedev->mdev = true;
+
     /*
      * All vfio-ccw devices are believed to operate in a way compatible with
      * discarding of memory in RAM blocks, ie. pages pinned in the host are