[SCSI] fix ABORTED_COMMAND looping forever problem

Instead of terminating after five retries, commands terminated by
ABORTED_COMMAND sense are retrying forever.  The problem was
introduced by:

commit b60af5b0
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Mon Nov 3 15:56:47 2008 -0500

    [SCSI] simplify scsi_io_completion()

Which introduced an error whereby ABORTED_COMMAND now gets erroneously
retried in scsi_io_completion.  Fix this by returning the behaviour
back to the default no retry.

Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>