usb: phy: tahvo: add IRQ check

The driver neglects to check the result of platform_get_irq()'s call and
blithely passes the negative error codes to request_threaded_irq() (which
takes *unsigned* IRQ #), causing it to fail with -EINVAL, overriding an
original error code.  Stop calling request_threaded_irq() with the invalid
IRQ #s.

Fixes: 9ba96ae5 ("usb: omap1: Tahvo USB transceiver driver")
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/8280d6a4-8e9a-7cfe-1aa9-db586dc9afdf@omp.ruSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/phy/phy-tahvo.c

@@ -393,7 +393,9 @@ static int tahvo_usb_probe(struct platform_device *pdev)
 
 	dev_set_drvdata(&pdev->dev, tu);
 
-	tu->irq = platform_get_irq(pdev, 0);
+	tu->irq = ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
 	ret = request_threaded_irq(tu->irq, NULL, tahvo_usb_vbus_interrupt,
 				   IRQF_ONESHOT,
 				   "tahvo-vbus", tu);