ASoC: fsl_ssi: Fix irq error check

Commit 2ffa5310 ("ASoC: fsl_ssi: Fix module unbound") changed the way to
retrieve the irq number from irq_of_parse_and_map() to platform_get_irq(), but
missed to updated the irq error check accordingly.

We should test for negative irq number and propagate it in the case of error.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_ssi.c

@@ -1362,9 +1362,9 @@ static int fsl_ssi_probe(struct platform_device *pdev)
 	}
 
 	ssi_private->irq = platform_get_irq(pdev, 0);
-	if (!ssi_private->irq) {
+	if (ssi_private->irq < 0) {
 		dev_err(&pdev->dev, "no irq for node %s\n", np->full_name);
-		return -ENXIO;
+		return ssi_private->irq;
 	}
 
 	/* Are the RX and the TX clocks locked? */