atp870u: Major rework

This patch series removes the first level of crap from atp870u - the worst (in-tree) SCSI driver [1] and then cleans up the code a bit.

First the driver is converted to C from something that looks like a (bad) assembler code: use of tmport for all I/O accesses and gotos all over the code.
Then I/O access wrappers are introduced.
Finally, is870, is880 and is885 are unified and two of them removed.

After that, some cleanups are done. There's still a lot of work left to do.

Tested on AEC-6710D (ATP870IU-C).

[1] http://www.spinics.net/lists/linux-scsi/msg81142.html

 atp870u.c | 3707 +++++++++++++++++---------------------------------------------
 atp870u.h |    4
 2 files changed, 1064 insertions(+), 2647 deletions(-)