clk: samsung: exynos5: Fix possible NULL pointer exception on platform_device_alloc() failure

During initialization of subdevices if platform_device_alloc() failed,
returned NULL pointer will be later dereferenced.  Add proper error
paths to exynos5_clk_register_subcmu().  The return value of this
function is still ignored because at this stage of init there is nothing
we can do.

Fixes: b06a532b ("clk: samsung: Add Exynos5 sub-CMU clock driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/samsung/clk-exynos5-subcmu.c

@@ -136,15 +136,21 @@ static int __init exynos5_clk_register_subcmu(struct device *parent,
 {
 	struct of_phandle_args genpdspec = { .np = pd_node };
 	struct platform_device *pdev;
+	int ret;
 
 	pdev = platform_device_alloc(info->pd_name, -1);
+	if (!pdev)
+		return -ENOMEM;
+
 	pdev->dev.parent = parent;
 	pdev->driver_override = "exynos5-subcmu";
 	platform_set_drvdata(pdev, (void *)info);
 	of_genpd_add_device(&genpdspec, &pdev->dev);
-	platform_device_add(pdev);
+	ret = platform_device_add(pdev);
+	if (ret)
+		platform_device_put(pdev);
 
-	return 0;
+	return ret;
 }
 
 static int __init exynos5_clk_probe(struct platform_device *pdev)