OLED panel brightness support

[Sam Ravnborg]

Hi Daniel.

> >
> > Hmm... browsing backlight code I see that FB_EARLY_EVENT_BLANK and FB_R_EARLY_EVENT_BLANK
> > are not used - time to delete some code...
> 
> 5.3-rc1 has patches from me to fix that, it's gone already. These two
> events are gone from the backlight code. They're still used by the lcd
> driver stuff in backlight/lcd.c.

backlight/lcd.c call the callbacks.
But the callbacks are never set so we can drop the support.

Patch coming, you are cc:

	Sam