leds: call led_pwm_set() in leds-pwm to enforce default LED_OFF

BugLink: https://bugs.launchpad.net/bugs/1811077

commit f1670336 upstream.

Some PWMs are disabled by default or the default pin setting
does not match the LED_OFF state (e.g., active-low leds).
Hence, the driver may end up reporting 0 brightness, but
the leds are actually on using full brightness, because
it never enforces its default configuration.
So enforce it by calling led_pwm_set() after successfully
registering the device.

Tested on a Phytec phyFLEX i.MX6Q board based on kernel
v3.19.5.
Signed-off-by: Markus Hofstaetter <markus.hofstaetter@ait.ac.at>
Tested-by: Markus Hofstaetter <markus.hofstaetter@ait.ac.at>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/leds/leds-pwm.c

@@ -132,6 +132,7 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
 	ret = led_classdev_register(dev, &led_data->cdev);
 	if (ret == 0) {
 		priv->num_leds++;
+		led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
 	} else {
 		dev_err(dev, "failed to register PWM led for %s: %d\n",
 			led->name, ret);