Staging: comedi: 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>
@disable is_null@
identifier f;
expression E;
identifier fld;
statement S;
@@

+ if (E == NULL) S
  f(...,E->fld,...);
- if (E == NULL) S

@@
identifier f;
expression E;
identifier fld;
statement S;
@@

+ if (!E) S
  f(...,E->fld,...);
- if (!E) S
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/comedi/drivers/usbduxfast.c

@@ -1675,15 +1675,15 @@ static int usbduxfast_detach(comedi_device * dev)
 {
 	usbduxfastsub_t *usbduxfastsub_tmp;
 
-#ifdef CONFIG_COMEDI_DEBUG
-	printk("comedi%d: usbduxfast: detach usb device\n", dev->minor);
-#endif
-
 	if (!dev) {
 		printk("comedi?: usbduxfast: detach without dev variable...\n");
 		return -EFAULT;
 	}
 
+#ifdef CONFIG_COMEDI_DEBUG
+	printk("comedi%d: usbduxfast: detach usb device\n", dev->minor);
+#endif
+
 	usbduxfastsub_tmp = dev->private;
 	if (!usbduxfastsub_tmp) {
 		printk("comedi?: usbduxfast: detach without ptr to usbduxfastsub[]\n");