fsi: fsi-occ: fix return value check in occ_probe()

In case of error, the function platform_device_register_full()
returns ERR_PTR() and never returns NULL. The NULL test in the
return value check should be replaced with IS_ERR().
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Joel Stanley <joel@jms.id.au>

drivers/fsi/fsi-occ.c

@@ -555,7 +555,7 @@ static int occ_probe(struct platform_device *pdev)
 
 	hwmon_dev_info.id = occ->idx;
 	hwmon_dev = platform_device_register_full(&hwmon_dev_info);
-	if (!hwmon_dev)
+	if (IS_ERR(hwmon_dev))
 		dev_warn(dev, "failed to create hwmon device\n");
 
 	return 0;