spi: davinci: fix handling platform_get_irq result

Author: Andrzej Hajda <a.hajda@samsung.com>

The function can return negative value.

The problem has been detected using proposed semantic patch
scripts/coccinelle/tests/assign_signed_to_unsigned.cocci [1].

[1]: http://permalink.gmane.org/gmane.linux.kernel/2046107

Signed-off-by: Andrzej Hajda 
Signed-off-by: Mark Brown 
---
 drivers/spi/spi-davinci.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
 
diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
index 3cf9faa..a85d863 100644
--- a/drivers/spi/spi-davinci.c
+++ b/drivers/spi/spi-davinci.c
@@ -992,11 +992,12 @@ static int davinci_spi_probe(struct platform_device *pdev)
 		goto free_master;
 	}
 
-	dspi->irq = platform_get_irq(pdev, 0);
-	if (dspi->irq <= 0) {
+	ret = platform_get_irq(pdev, 0);
+	if (ret == 0)
 		ret = -EINVAL;
+	if (ret < 0)
 		goto free_master;
-	}
+	dspi->irq = ret;
 
 	ret = devm_request_threaded_irq(&pdev->dev, dspi->irq, davinci_spi_irq,
 				dummy_thread_fn, 0, dev_name(&pdev->dev), dspi);