The MT8183 display PWM device will not work until the associated
power-domain is enabled. Add the power-domain reference to the node
allows the display PWM driver to operate and the backlight turn on.

Fixes: f15722c0 ("arm64: dts: mt8183: Add pwm and backlight node")
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org>
Link: https://lore.kernel.org/r/20210113215723.71966-1-enric.balletbo@collabora.comSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>