s390x: pv: Fix diag318 PV fencing

s390x: pv: Fix diag318 PV fencing

Diag318 fencing needs to be determined on the current VM PV state and
not on the state that the VM has when we create the CPU model.

Fixes: fabdada935 ("s390: guest support for diagnose 0x318")
Reported-by: Marc Hartmayer <[email protected]>
Signed-off-by: Janosch Frank <[email protected]>
Tested-by: Marc Hartmayer <[email protected]>
Reviewed-by: Christian Borntraeger <[email protected]>
Reviewed-by: Collin Walling <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Message-Id: <20201022103135[email protected]>
Signed-off-by: Cornelia Huck <[email protected]>