When using virtio-scsi, we multiply the READ(10) data_size by
a block factor twice when building the I/O.  This is fine,
since it's only 1 for SCSI disks, but let's clean it up.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <20170510155359.32727-2-farman@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>