spi: ppc4xx: handle irq_of_parse_and_map() errors

Zero and negative number is not a valid IRQ for in-kernel code and the
irq_of_parse_and_map() function returns zero on error.  So this check for
valid IRQs should only accept values > 0.

Fixes: 44dab88e ("spi: add spi_ppc4xx driver")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Link: https://patch.msgid.link/20240724084047.1506084-1-make24@iscas.ac.cnSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-ppc4xx.c

@@ -413,6 +413,9 @@ static int spi_ppc4xx_of_probe(struct platform_device *op)
 
 	/* Request IRQ */
 	hw->irqnum = irq_of_parse_and_map(np, 0);
+	if (hw->irqnum <= 0)
+		goto free_host;
+
 	ret = request_irq(hw->irqnum, spi_ppc4xx_int,
 			  0, "spi_ppc4xx_of", (void *)hw);
 	if (ret) {