KVM: s390: Enable the LPP facility for guests

The Load-Program-Parameter Facility is available for guests without
any further ado, so we should indicate its availability by setting
facility bit 40 if it is supported by the host.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>