atapi: abort transfers with 0 byte limits

We're supposed to abort on transfers like this, unless we fill
Word 125 of our IDENTIFY data with a default transfer size, which
we don't currently do.

This is an ATA error, not a SCSI/ATAPI one.
See ATA8-ACS3 sections 7.17.6.49 or 7.21.5.

If we don't do this, QEMU will loop forever trying to transfer
zero bytes, which isn't particularly useful.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1442253685-23349-2-git-send-email-jsnow@redhat.com
