ARM: u300: fix return value check in __u300_init_boardpower()

In case of error, the function syscon_node_to_regmap() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check should
be replaced with IS_ERR().
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>

arch/arm/mach-u300/regulator.c

@@ -69,9 +69,9 @@ static int __init __u300_init_boardpower(struct platform_device *pdev)
 		return -ENODEV;
 	}
 	regmap = syscon_node_to_regmap(syscon_np);
-	if (!regmap) {
+	if (IS_ERR(regmap)) {
 		pr_crit("U300: could not locate syscon regmap\n");
-		return -ENODEV;
+		return PTR_ERR(regmap);
 	}
 
 	main_power_15 = regulator_get(&pdev->dev, "vana15");