video: backlight: Drop maximum brightness override for brightness zero

stable inclusion
from stable-5.10.80
commit 7d0341b37d9763a6e7e1a3b7464d115839e30246
bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d0341b37d9763a6e7e1a3b7464d115839e30246



--------------------------------

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>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>