can: mcp251x: fix coccinelle warnings

drivers/net/can/spi/mcp251x.c:953:7-27: ERROR: Threaded IRQ with no primary handler requested without IRQF_ONESHOT

 Make sure threaded IRQs without a primary handler are always request with
 IRQF_ONESHOT

Generated by: scripts/coccinelle/misc/irqf_oneshot.cocci

CC: Stefano Babic <sbabic@denx.de>
CC: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/mcp251x.c

@@ -951,7 +951,7 @@ static int mcp251x_open(struct net_device *net)
 	priv->tx_len = 0;
 
 	ret = request_threaded_irq(spi->irq, NULL, mcp251x_can_ist,
-				   flags, DEVICE_NAME, priv);
+				   flags | IRQF_ONESHOT, DEVICE_NAME, priv);
 	if (ret) {
 		dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);
 		mcp251x_power_enable(priv->transceiver, 0);