can: at91_can: at91_open(): forward request_irq()'s return value in case or an error

If request_irq() fails, forward the return value.

Link: https://lore.kernel.org/all/20231005-at91_can-rx_offload-v2-15-9987d53600e0@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/at91_can.c

@@ -1128,11 +1128,10 @@ static int at91_open(struct net_device *dev)
 		goto out;
 
 	/* register interrupt handler */
-	if (request_irq(dev->irq, at91_irq, IRQF_SHARED,
-			dev->name, dev)) {
-		err = -EAGAIN;
+	err = request_irq(dev->irq, at91_irq, IRQF_SHARED,
+			  dev->name, dev);
+	if (err)
 		goto out_close;
-	}
 
 	/* start chip and queuing */
 	at91_chip_start(dev);