rtc: asm9260: add the missed check for devm_clk_get

The driver misses a check for devm_clk_get().
Add the check to fix it.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Link: https://lore.kernel.org/r/20191214074528.16806-1-hslester96@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-asm9260.c

@@ -264,6 +264,9 @@ static int asm9260_rtc_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->iobase);
 
 	priv->clk = devm_clk_get(dev, "ahb");
+	if (IS_ERR(priv->clk))
+		return PTR_ERR(priv->clk);
+
 	ret = clk_prepare_enable(priv->clk);
 	if (ret) {
 		dev_err(dev, "Failed to enable clk!\n");