arm64: dts: mediatek: add MT8167 pumpkin board dts

arm64: dts: mediatek: add MT8167 pumpkin board dts

The pumpkin board is  made by Gossamer Engineering and is using
a MediaTek SoC. The board currently comes in two available version:
MT8516 SoC and MT8167 SoC.
The board provides the following IOs: eMMC, NAND, SD card, USB type-A,
Ethernet, Wi-Fi, Bluetooth, Audio (jack out, 2 PDM port, 1 analog in),
serial over USB, HDMI, DSI, CSI, and an expansion header.

The board can be powered by battery and/or via a USB Type-C port and
is using a PMIC MT6392.

The eMMC and NAND are sharing pins and cannot be used together.

This commit is adding the basic boot support for the Pumpkin MT8167
board.

Signed-off-by: Fabien Parent <fparent@baylibre.com>
Link: https://lore.kernel.org/r/20201027194816.1227654-3-fparent@baylibre.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>