s390x: Rebuild IPLB for SCSI device directly from DIAG308

s390x: Rebuild IPLB for SCSI device directly from DIAG308

Because virtio-scsi type devices use a non-architected IPLB pbt code they cannot
be set and stored normally. Instead, the IPLB must be rebuilt during re-ipl.

As s390x does not natively support multiple boot devices, the devno field is
used to store the position in the boot order for the device.

Handling the rebuild as part of DIAG308 removes the need to check the devices
for invalid IPLBs later in the IPL.

Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20241020012953.1380075-17-jrossi@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>