Since the sht15 driver supports operation without an external vref
regulator the driver should use the new devm_regulator_get_optional() to
indicate that a stub regulator should not be provided.
Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
         * If a regulator is available,
         * query what the supply voltage actually is!
         */
-       data->reg = devm_regulator_get(data->dev, "vcc");
+       data->reg = devm_regulator_get_optional(data->dev, "vcc");
        if (!IS_ERR(data->reg)) {
                int voltage;