rtc: isl12057: use PTR_ERR_OR_ZERO to fix coccinelle warnings

drivers/rtc/rtc-isl12057.c:278:1-3: WARNING: PTR_RET can be used

 Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: coccinelle/api/ptr_ret.cocci

CC: Arnaud Ebalard <arno@natisbad.org>
CC: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/rtc/rtc-isl12057.c

@@ -275,10 +275,7 @@ static int isl12057_probe(struct i2c_client *client,
 	dev_set_drvdata(dev, data);
 
 	rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
-	if (IS_ERR(rtc))
-		return PTR_ERR(rtc);
-
-	return 0;
+	return PTR_ERR_OR_ZERO(rtc);
 }
 
 #ifdef CONFIG_OF