ARM: dts: rockchip: add rk3288-veyron-minnie backlight and panel settings

The pwm for Minnie's backlight needs to be above 1%, so adapt the start
of non-zero brightness accordingly. Minnie is also using a different
panel, so re-set the compatible property.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Douglas Anderson <dianders@chromium.org>