backlight: pwm_bl: Check the PWM state for initial backlight power state

If the PWM is not enabled the backlight initially should not be enabled
either if we have booted with DT and there is a phandle pointing to the
backlight node.

The patch extends the checks to decide if we should keep the backlight off
initially.

Signed-off-by: Peter Ujfalusi <[e-mail]>
Acked-by: Philipp Zabel <[e-mail]>
Reviewed-by: Thierry Reding <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/video/backlight/pwm_bl.c

···
 	if (!regulator_is_enabled(pb->power_supply))
 		return FB_BLANK_POWERDOWN;
 
+	/* The PWM is disabled, keep it like this */
+	if (!pwm_is_enabled(pb->pwm))
+		return FB_BLANK_POWERDOWN;
+
 	return FB_BLANK_UNBLANK;
 }