ide-pm: always pass 0 error to __blk_end_request_all

ide_pm_execute_rq exectures a PM request synchronously, and in the failure
case where it calls __blk_end_request_all it never checks the error field
passed to the end_io callback, so don't bother setting it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>