aha152x.c - Cleanup, need help in testing and auditing

In motivation for the !use_sg cleanup and use of accessors I needed to do some restructuring of the aha152x.c driver.

I have tried to be as careful as I could, but with out the hardware for testing, it is hard. Christoph and James You are signed on a couple of the last patches to this driver So you are probably somewhat familiar with the code. Could you please review the patchset to see that nothing is broken.

If any one has an Hardware that uses aha152x.c, please help me with testing this patchset. If it does not work could you please do a short bisect of which patch breaks out of the 4.

The problematic parts were that the driver writes all over the scsi_cmnd members in couple of places. To untangle that I divided the work to stages for easier review and testing. I was very verbose at each patch explanation, mainly for myself to try and prove that the changes are sound.

[patch 1/4] aha152x.c - Preliminary fixes and comments
Some weird typos and some hard coded numbers made the code very hard to understand.

[patch 2/4] aha152x.c - Clean Reset path
On the Reset code path the driver would save, write, than restore scsi_cmnd members. Here I propose a solution that does not need to do that.

[patch 3/4] aha152x.c - Fix check_condition code-path
In case of a Status return from a target. The driver would re-queue the command with a REQUEST_SENSE read. Again save, write, restore. I cleaned that up to a stage I can be happy with. Also while at it I fixed a BUG with "resid".

[patch 4/4] aha152x.c - use data accessors and !use_sg cleanup
And now everything is ready for this one.

Thanks for any help
Boaz