Merge tag 'kvm-s390-next-4.17-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: fixes and features

- more kvm stat counters
- virtio gpu plumbing. The 3 non-KVM/s390 patches have Acks from
  Bartlomiej Zolnierkiewicz, Heiko Carstens and Greg Kroah-Hartman
  but all belong together to make virtio-gpu work as a tty. So
  I carried them in the KVM/s390 tree.
- document some KVM_CAPs
- cpu-model only facilities
- cleanups