s390/ipl: cast to SCSIDevice directly

Coverity notes that the result of object_dynamic_cast() to
SCSIDevice is not checked in s390_gen_initial_iplp(); as
we know that we always have a SCSIDevice in that branch,
we can instead cast via SCSI_DEVICE directly.

Coverity: CID 1401098
Fixes: 44445d86 ("s390 vfio-ccw: Add bootindex property and IPLB data")
Message-Id: <20190502155516.12415-1-cohuck@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NCornelia Huck <cohuck@redhat.com>

hw/s390x/ipl.c

@@ -374,8 +374,7 @@ static bool s390_gen_initial_iplb(S390IPLState *ipl)
     if (ccw_dev) {
         switch (devtype) {
         case CCW_DEVTYPE_SCSI:
-            sd = (SCSIDevice *) object_dynamic_cast(OBJECT(dev_st),
-                                                           TYPE_SCSI_DEVICE);
+            sd = SCSI_DEVICE(dev_st);
             ipl->iplb.len = cpu_to_be32(S390_IPLB_MIN_QEMU_SCSI_LEN);
             ipl->iplb.blk0_len =
                 cpu_to_be32(S390_IPLB_MIN_QEMU_SCSI_LEN - S390_IPLB_HEADER_LEN);