backlight: lm3630a: Don't set bl->props.brightness in get_brightness

[ Upstream commit 4bf7ddd2d2f0f8826f25f74c7eba4e2c323a1446 ]

There's no need to set bl->props.brightness, the get_brightness function
is just supposed to return the current brightness and not touch the
struct.

With that done we can also remove the 'goto out' and just return the
value.

Fixes: 0c2a665a ("backlight: add Backlight driver for lm3630 chip")
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20240220-lm3630a-fixups-v1-2-9ca62f7e4a33@z3ntu.xyz


Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>