can: m_can: m_can_close(): don't call free_irq() for IRQ-less devices

In commit b382380c0d ("can: m_can: Add hrtimer to generate software
interrupt") support for IRQ-less devices was added. Instead of an
interrupt, the interrupt routine is called by a hrtimer-based polling
loop.

That patch forgot to change free_irq() to be only called for devices
with IRQs. Fix this, by calling free_irq() conditionally only if an
IRQ is available for the device (and thus has been requested
previously).

Fixes: b382380c0d ("can: m_can: Add hrtimer to generate software interrupt")
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>
Link: https://patch.msgid.link/20240930-m_can-cleanups-v1-1-001c579cdee4@pengutronix.de
Cc: <stable@vger.kernel.org> # v6.6+
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/m_can.c

@@ -1765,6 +1765,7 @@ static int m_can_close(struct net_device *dev)
 	netif_stop_queue(dev);
 
 	m_can_stop(dev);
+	if (dev->irq)
 		free_irq(dev->irq, dev);
 
 	m_can_clean(dev);