regulator: core: Fix regualtor_ena_gpio_free not to access pin after freeing

After freeing pin from regulator_ena_gpio_free, loop can access
the pin. So this patch fixes not to access pin after freeing.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
static ssize_t num_users_show(struct device *dev, struct device_attribute *attr,
			      char *buf)
{
	struct regulator_dev *rdev = dev_get_drvdata(dev);
	return sprintf(buf, "%d\n", rdev->use_count);
}

static ssize_t num_users_show(struct device *dev, struct device_attribute *attr,
			      char *buf)
{
	struct regulator_dev *rdev = dev_get_drvdata(dev);
	return sprintf(buf, "%d\n", rdev->use_count);
}
