regulator: gpio-regulator: fix can't find regulator node in dt

Need initilize of_node in regulator config when register regulator,
otherwise regulator driver think it is no-dt device.

in regulator_dev_lookup
list_for_each_entry(r, &regulator_list, list)
	if (r->dev.parent &&
		node == r->dev.of_node)
			return r

r->dev.of_noe will be zero if miss config in cfg.
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/gpio-regulator.c

@@ -303,6 +303,7 @@ static int __devinit gpio_regulator_probe(struct platform_device *pdev)
 	cfg.dev = &pdev->dev;
 	cfg.init_data = config->init_data;
 	cfg.driver_data = drvdata;
+	cfg.of_node = np;
 
 	if (config->enable_gpio >= 0)
 		cfg.ena_gpio = config->enable_gpio;