libata: remove the done callback from ata_scsi_args

It's always the scsi_done callback, and we can get at that easily
in the place where ->done is called.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/libata-scsi.c

@@ -2061,7 +2061,6 @@ struct ata_scsi_args {
 	struct ata_device	*dev;
 	u16			*id;
 	struct scsi_cmnd	*cmd;
-	void			(*done)(struct scsi_cmnd *);
 };
 
 /**
@@ -2140,7 +2139,7 @@ static void ata_scsi_rbuf_fill(struct ata_scsi_args *args,
 
 	if (rc == 0)
 		cmd->result = SAM_STAT_GOOD;
-	args->done(cmd);
+	cmd->scsi_done(cmd);
 }
 
 /**
@@ -4357,7 +4356,6 @@ void ata_scsi_simulate(struct ata_device *dev, struct scsi_cmnd *cmd)
 	args.dev = dev;
 	args.id = dev->id;
 	args.cmd = cmd;
-	args.done = cmd->scsi_done;
 
 	switch(scsicmd[0]) {
 	case INQUIRY: