Simple refactoring so that the blk_factor adjustment is
moved into virtio_scsi_read_many routine, in preparation
for another change.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
Message-Id: <20170510155359.32727-3-farman@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>