[ide] suppress output of error messages for non-existant interfaces

From: Prarit Bhargava <prarit@sgi.com>

Suppress output of "Wait for ready failed before probe !" messages for 
non-existant interfaces.

Please see 
http://marc.theaimsgroup.com/?l=linux-ide&m=110553792013649&w=2 for 
further context on this patch.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-probe.c

@@ -749,7 +749,7 @@ static void probe_hwif(ide_hwif_t *hwif)
 	 *  
 	 *  BenH.
 	 */
-	if (wait_hwif_ready(hwif))
+	if (wait_hwif_ready(hwif) == -EBUSY)
 		printk(KERN_DEBUG "%s: Wait for ready failed before probe !\n", hwif->name);
 
 	/*