spi: xlp: fix error return code in xlp_spi_probe()

platform_get_irq() returns an error code, but the spi-xlp driver ignores
it and always returns -EINVAL. This is not correct and, prevents
-EPROBE_DEFER from being propagated properly.

Notice that platform_get_irq() no longer returns 0 on error:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e330b9a6bb35dc7097a4f02cb1ae7b6f96df92af

Print and propagate the return value of platform_get_irq on failure.

This issue was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-xlp.c

@@ -393,8 +393,8 @@ static int xlp_spi_probe(struct platform_device *pdev)
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
-		dev_err(&pdev->dev, "no IRQ resource found\n");
-		return -EINVAL;
+		dev_err(&pdev->dev, "no IRQ resource found: %d\n", irq);
+		return irq;
 	}
 	err = devm_request_irq(&pdev->dev, irq, xlp_spi_interrupt, 0,
 			pdev->name, xspi);