Set rq->errors at ide_complete_rq() call sites and then pass
error value to ide_complete_rq().

[ Some rq->errors assignments look really wrong but this patch
  leaves them alone to not introduce too many changes at once. ]

There should be no functional changes caused by this patch.
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>