can: flexcan: fix the return value handle for platform_get_irq()

There is no possible for platform_get_irq() to return 0
and the return value of platform_get_irq() is more sensible
to show the error reason.

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/all/20230731075252.359965-1-ruanjinjie@huawei.com


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>