[SCSI] aha152x: Clean Reset path

What Reset code was doing:  Save command's important/dangerous
Info on stack. NULL those members from scsi_cmnd.
Issue a Reset. wait for it to finish than restore members
and return.

What I do is save or NULL nothing. But use the "resetting"
hint in aha152x_internal_queue() to NULL out working members
and leave struct scsi_cmnd alone.

The indent here looks funny but it will change/drop in last
patch and it is clear this way what changed.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>