hw/s390x: add Control-Program Identification to QOM

hw/s390x: add Control-Program Identification to QOM

Add Control-Program Identification (CPI) data to the QEMU Object
Model (QOM), along with the timestamp in which the data was received
as shown below.

virsh # qemu-monitor-command vm --pretty '{"execute":"qom-list",
"arguments":{"path":"/machine/sclp/s390-sclp-event-facility/sclpcpi"}}'
{
  "return": [
    [...]
    {
      "name": "system_level",
      "type": "uint64"
    },
    {
      "name": "system_name",
      "type": "string"
    },
    {
      "name": "system_type",
      "type": "string"
    },
    {
      "name": "timestamp",
      "type": "uint64"
    },
    {
      "name": "sysplex_name",
      "type": "string"
    }
  ],
  "id": "libvirt-14"
}

Example CPI data:
virsh # qemu-monitor-command vm --pretty '{"execute":"qom-get",
"arguments":{"path":"/machine/sclp/s390-sclp-event-facility/sclpcpi",
"property":"system_type"}}'
{
  "return": "LINUX   ",
  "id": "libvirt-18"
}
virsh # qemu-monitor-command vm --pretty '{"execute":"qom-get",
"arguments":{"path":"/machine/sclp/s390-sclp-event-facility/sclpcpi",
"property":"system_name"}}'
{
  "return": "TESTVM  ",
  "id": "libvirt-19"
}
virsh # qemu-monitor-command vm --pretty '{"execute":"qom-get",
"arguments":{"path":"/machine/sclp/s390-sclp-event-facility/sclpcpi",
"property":"sysplex_name"}}'
{
  "return": "PLEX    ",
  "id": "libvirt-20"
}
virsh # qemu-monitor-command vm --pretty '{"execute":"qom-get",
"arguments":{"path":"/machine/sclp/s390-sclp-event-facility/sclpcpi",
"property":"system_level"}}'
{
  "return": 74872343805430528,
  "id": "libvirt-21"
}
virsh # qemu-monitor-command vm --pretty '{"execute":"qom-get",
"arguments":{"path":"/machine/sclp/s390-sclp-event-facility/sclpcpi",
"property":"timestamp"}}'
{
  "return": 1748866753433923000,
  "id": "libvirt-22"
}

Signed-off-by: Shalini Chellathurai Saroja <shalini@linux.ibm.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20250616140107.990538-3-shalini@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>