KVM: s390: implement subfunction processor calls

KVM: s390: implement subfunction processor calls

BugLink: https://bugs.launchpad.net/bugs/1836153
While we will not implement interception for query functions yet, we can
and should disable functions that have a control bit based on the given
CPU model.

Let us start with enabling the subfunction interface.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
(cherry picked from commit 346fa2f891c71a9b98014f8f62c15f4c7dd95ec1)
Signed-off-by: Frank Heimes <frank.heimes@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>