arm64: dts: rockchip: Add internal display support to rk3399-pinephone-pro

The phone's display is using a Hannstar LCD panel. Support it by adding a
panel DT node and all needed nodes (backlight, MIPI DSI, regulators, etc).

Signed-off-by: Martijn Braam <martijn@brixit.nl>
Co-developed-by: Kamil Trzciński <ayufan@ayufan.eu>
Signed-off-by: Kamil Trzciński <ayufan@ayufan.eu>
Co-developed-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Ondrej Jirman <megi@xff.cz>
Link: https://lore.kernel.org/r/20230328073309.1743112-2-javierm@redhat.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>