Remove machine code for the s390-virtio machine, but keep functions
useful for the ccw machine.

Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>