powerpc/BSR: fix device_create() return value check

Use IS_ERR() instead of comparing to NULL.
Signed-off-by: Jani Nikula <ext-jani.1.nikula@nokia.com>
Acked-by: Sonny Rao <sonnyrao@us.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/char/bsr.c

@@ -252,7 +252,7 @@ static int bsr_add_node(struct device_node *bn)
 
 		cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
 						cur, cur->bsr_name);
-		if (!cur->bsr_device) {
+		if (IS_ERR(cur->bsr_device)) {
 			printk(KERN_ERR "device_create failed for %s\n",
 			       cur->bsr_name);
 			cdev_del(&cur->bsr_cdev);