backlight: fix pwm_bl.c to notify platform code when suspending

When suspending, pwm-bl sets duty cycle to 0, and shuts down the pwm
device.

This patch ensure that the platform code is called before that
(through the notify callback_, leaving a chance for the platform code
to configure GPIOs (shutting off the backlight, for example), much like
it is done during normal operations.
Signed-off-by: Marc Zyngier <maz@misterjones.org>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

drivers/video/backlight/pwm_bl.c

@@ -145,6 +145,8 @@ static int pwm_backlight_suspend(struct platform_device *pdev,
 	struct backlight_device *bl = platform_get_drvdata(pdev);
 	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
 
+	if (pb->notify)
+		pb->notify(0);
 	pwm_config(pb->pwm, 0, pb->period);
 	pwm_disable(pb->pwm);
 	return 0;