arm64: dts: Add Mediatek SoC MT8192 and evaluation board dts and Makefile

Add basic chip support for Mediatek MT8192

Signed-off-by: Seiya Wang <seiya.wang@mediatek.com>
Link: https://lore.kernel.org/r/20201030092207.26488-2-seiya.wang@mediatek.com


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>