in a TAILQ. Re-arrange some of the ecb elements so that they can stay
stable through alloc/free cycles while the rest get bzero'd.
- Use the tag_id from the ecb rather than fro the ccb. The latter is only
for target mode.
- Honor the ccb flags for tag_action when deciding whether to do a tagged
or untagged transaction.
- Re-arrange autosense completion so that it works correctly in failure
cases.
- Turn on the PI_TAG_ABLE flag so that CAM will send us tagged transactions.
This enables tagged queueing in the driver.