spi: omap-uwire: add missing iounmap

This fixes the following coccicheck warning:
linux-2.6/drivers/spi/spi-omap-uwire.c:485:2-8: ERROR: missing iounmap; ioremap on line 471 and execution via conditional on line 481
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-omap-uwire.c

@@ -478,6 +478,7 @@ static int uwire_probe(struct platform_device *pdev)
 		status = PTR_ERR(uwire->ck);
 		dev_dbg(&pdev->dev, "no functional clock?\n");
 		spi_master_put(master);
+		iounmap(uwire_base);
 		return status;
 	}
 	clk_enable(uwire->ck);