video: backlight: Drop maximum brightness override for brightness zero

commit 33a5471f upstream.

The note in c2adda27 ("video: backlight: Add of_find_backlight helper
in backlight.c") says that gpio-backlight uses brightness as power state.
This has been fixed since in ec665b75 ("backlight: gpio-backlight:
Correct initial power state handling") and other backlight drivers do not
require this workaround. Drop the workaround.

This fixes the case where e.g. pwm-backlight can perfectly well be set to
brightness 0 on boot in DT, which without this patch leads to the display
brightness to be max instead of off.

Fixes: c2adda27 ("video: backlight: Add of_find_backlight helper in backlight.c")
Cc: <stable@vger.kernel.org> # 5.4+
Cc: <stable@vger.kernel.org> # 4.19.x: ec665b75: backlight: gpio-backlight: Correct initial power state handling
Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>