arm64: dts: exynos: add minimal support for exynosautov9 sadk board

SADK(Samsung Automotive Development Kit) is the development kit to
evaluate Exynos Auto v9 SoC. It has 16GB LPDDR4 DRAM and two
256GB Samsung UFS. This patch enables only serial console and ufs0
device.

Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Link: https://lore.kernel.org/r/20211012002314.38965-4-chanho61.park@samsung.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>