can: xilinx_can: xcan_probe(): check for error irq

can: xilinx_can: xcan_probe(): check for error irq

For the possible failure of the platform_get_irq(), the returned irq
could be error number and will finally cause the failure of the
request_irq().

Consider that platform_get_irq() can now in certain cases return
-EPROBE_DEFER, and the consequences of letting request_irq()
effectively convert that into -EINVAL, even at probe time rather than
later on. So it might be better to check just now.

Fixes: 7b2a5faf4fb9 ("can: xilinx CAN controller support")
Link: https://lore.kernel.org/all/20211224021324.1447494-1-jiasheng@iscas.ac.cn
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>