scsi: core: return BLK_STS_OK for DID_OK in __scsi_error_from_host_byte()

When converting __scsi_error_from_host_byte() to BLK_STS error codes the
case DID_OK was forgotten, resulting in it always returning an error.

Fixes: 2a842aca

 ("block: introduce new block status code type")
Cc: Doug Gilbert <dgilbert@interlog.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>