arm64: dts: meson: add libretech-pc support

Add support for the Amlogic based libretech-pc platform.
This platform comes with 2 variant, based on the s905d or s912 SoC.

Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
[narmstrong: update board/amlogic/q200/MAINTAINERS]
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>