Commit "virtio-scsi: use standard-headers" added
cdb and sense into req/rep structures, which
breaks uses of sizeof for these structures,
since qemu adds its own arrays on top.
To fix, redefine CDB/sense field size to 0.
Reported-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>