drivers/ata: Move a dereference below a NULL test

If the NULL test is necessary, then the dereference should be moved below
the NULL test.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
type T;
expression E;
identifier i,fld;
statement S;
@@

- T i = E->fld;
+ T i;
  ... when != E
      when != i
  if (E == NULL) S
+ i = E->fld;
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_at91.c

@@ -312,11 +312,12 @@ static int __devinit pata_at91_probe(struct platform_device *pdev)
 static int __devexit pata_at91_remove(struct platform_device *pdev)
 {
 	struct ata_host *host = dev_get_drvdata(&pdev->dev);
-	struct at91_ide_info *info = host->private_data;
+	struct at91_ide_info *info;
 	struct device *dev = &pdev->dev;
 
 	if (!host)
 		return 0;
+	info = host->private_data;
 
 	ata_host_detach(host);