xilinx_spi: test below 0 on unsigned irq in xilinx_spi_probe()

xilinx_spi->irq is unsigned, so the test fails
Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Andrei Konovalov <akonovalov@ru.mvista.com>
Cc: Yuri Frolov <yfrolov@ru.mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/xilinx_spi.c

@@ -353,11 +353,12 @@ static int __init xilinx_spi_probe(struct platform_device *dev)
 		goto put_master;
 	}
 
-	xspi->irq = platform_get_irq(dev, 0);
-	if (xspi->irq < 0) {
+	ret = platform_get_irq(dev, 0);
+	if (ret < 0) {
 		ret = -ENXIO;
 		goto unmap_io;
 	}
+	xspi->irq = ret;
 
 	master->bus_num = pdata->bus_num;
 	master->num_chipselect = pdata->num_chipselect;