hwmon: (sht15) Check return value of regulator_enable()

Not having power is a pretty serious error so check that we are able to
enable the supply and error out if we can't.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org #3.8+; 3.0+ will need manual backport
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/sht15.c

@@ -965,7 +965,13 @@ static int sht15_probe(struct platform_device *pdev)
 		if (voltage)
 			data->supply_uv = voltage;
 
-		regulator_enable(data->reg);
+		ret = regulator_enable(data->reg);
+		if (ret != 0) {
+			dev_err(&pdev->dev,
+				"failed to enable regulator: %d\n", ret);
+			return ret;
+		}
+
 		/*
 		 * Setup a notifier block to update this if another device
 		 * causes the voltage to change