Merge remote-tracking branch 'agraf/s390-for-upstream' into staging

* agraf/s390-for-upstream:
  s390: reset avail and used index on reboot
  S390: dont call system_shutdown on disabled wait
  S390: remove default cdrom, sd-card and floppy support
  S390: support reboot for kvm on s390
  S390: reboot: reset device pages on reboot
  S390: fix error handling on kernel and initrd failures
  S390: fix kernel_commandline handling