arm64: dts: mediatek: Add device-tree for MT8195 Demo board

Add basic device-tree for the MT8195 Demo board. The
Demo board is made by MediaTek and has a MT8195 SoC,
associated with the MT6359 and MT6360 PMICs, and
the MT7921 connectivity chip.

The IOs available on that board are:
* 1 USB Type-C connector with DP aux mode support
* 1 USB Type-A connector
* 1 full size HDMI RX and 1 full size HDMI TX connector
* 1 uSD slot
* 40 pins header
* SPI interface header
* 1 M.2 slot
* 1 audio jack
* 1 micro-USB port for serial debug
* 2 connectors for DSI displays
* 3 connectors for CSI cameras
* 1 connector for a eDP panel
* 1 MMC storage

This commit adds basic support in order to be able to boot.

Signed-off-by: Fabien Parent <fparent@baylibre.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Link: https://lore.kernel.org/r/20220415150003.1793063-3-fparent@baylibre.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>