clk: s2mps11: Fix possible NULL pointer dereference

If parent device does not have of_node set the s2mps11_clk_parse_dt()
returned NULL. This NULL was later passed to of_clk_add_provider() which
dereferenced it in pr_debug() call.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/clk-s2mps11.c

@@ -132,7 +132,7 @@ static struct device_node *s2mps11_clk_parse_dt(struct platform_device *pdev)
 	int i;
 
 	if (!iodev->dev->of_node)
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	clk_np = of_find_node_by_name(iodev->dev->of_node, "clocks");
 	if (!clk_np) {