security: do not remember/recall labels for VFIO MDEVs

security: do not remember/recall labels for VFIO MDEVs

Commit dbf1f68410 ("security: do not remember/recall labels for VFIO")
rightly changed the DAC and SELinux labeling parameters to fix a problem
with "VFIO hostdevs" but really only addressed the PCI codepaths.
As a result, we can still encounter this with VFIO MDEVs such as
vfio-ccw and vfio-ap, which can fail on a hotplug:

  [test@host ~]# mdevctl stop -u 11f2d2bc-4083-431d-a023-eff72715c4f0
  [test@host ~]# mdevctl start -u 11f2d2bc-4083-431d-a023-eff72715c4f0
  [test@host ~]# cat disk.xml
    <hostdev mode='subsystem' type='mdev' model='vfio-ccw'>
      <source>
        <address uuid='11f2d2bc-4083-431d-a023-eff72715c4f0'/>
      </source>
      <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x3c51'/>
    </hostdev>
  [test@host ~]# virsh attach-device guest ~/disk.xml
  error: Failed to attach device from /home/test/disk.xml
  error: Requested operation is not valid: Setting different SELinux label on /dev/vfio/3 which is already in use

Make the same changes as reported in commit dbf1f68410, for the mdev paths.

Reported-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>