[SCSI] libsas: Accept SAM_GOOD for ATAPI devices in sas_ata_task_done

A sas_task sent to an ATAPI devices returns SAM_GOOD if successful.
Therefore, we should treat this the same way we treat ATA commands
that succeed.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>