KVM: s390: protvirt: Add initial vm and cpu lifecycle handling

KVM: s390: protvirt: Add initial vm and cpu lifecycle handling

This contains 3 main changes:
1. changes in SIE control block handling for secure guests
2. helper functions for create/destroy/unpack secure guests
3. KVM_S390_PV_COMMAND ioctl to allow userspace dealing with secure
machines

Signed-off-by: Janosch Frank <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Cornelia Huck <[email protected]>
[[email protected]: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <[email protected]>