usb: imx21-hcd: fix error return code in imx21_probe()

platform_get_irq() returns an error code, but the imx21-hcd driver
ignores it and always returns -ENXIO. 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 error message 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/imx21-hcd.c

@@ -1849,8 +1849,10 @@ static int imx21_probe(struct platform_device *pdev)
 	if (!res)
 		return -ENODEV;
 	irq = platform_get_irq(pdev, 0);
-	if (irq < 0)
-		return -ENXIO;
+	if (irq < 0) {
+		dev_err(&pdev->dev, "Failed to get IRQ: %d\n", irq);
+		return irq;
+	}
 
 	hcd = usb_create_hcd(&imx21_hc_driver,
 		&pdev->dev, dev_name(&pdev->dev));