KVM: s390: guest large pages

This patch enables kvm to give large pages to the guest. The heavy
lifting is done by the hardware, the host only has to take care
of the PFMF instruction, which is also part of EDAT-1.

We also support the non-quiescing key setting facility if the host
supports it, to behave similar to the interpretation of sske.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>