This tweaks the hardware in two minor ways, being more forgiving
of what are either hardware bugs or hard-to-see driver bugs.

  - Some silicon seems to mis-handle dummy qtds on occasion,
    writing them into the qh and thus stopping progress unless
    something times it out and cancels it (scsi-eh etc).

    This initializes such qtds slightly differently, so some
    such cases will make the driver automatically recover, and
    so all such errors will fail in the same way.

  - In case of dodgy behavior with respect to unlinking, don't
    modify a field.  Silicon that's (wrongly) reading this will
    have a chance to read the old value while it's still valid.

Also minor diagnostic tweaks for better uniformity/usability.