ARM64: dts: meson-gxm: Add support for Khadas VIM2

The Khadas VIM2 is a Single Board Computer, respin of the origin
Khadas VIM board, using an Amlogic S912 SoC and more server oriented.

It provides the same external connectors and header pinout, plus a SPI
NOR Flash, a reprogrammable STM8S003 MCU, FPC Connector, Cooling FAN header
and Pogo Pads Arrays.

Cc: Gouwa <gouwa@szwesion.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>