arm64: dts: cix: Add sky1 base dts initial support

arm64: dts: cix: Add sky1 base dts initial support

CIX SKY1 SoC is high performance Armv9 SoC designed by Cixtech,
and Orion O6 is the motherboard launched by Radxa. See below for
detail:
https://docs.radxa.com/en/orion/o6/getting-started/introduction

In this commit, it only adds limited components for running initramfs
at Orion O6.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Enric Balletbo i Serra <eballetb@redhat.com>
Tested-by: Kajetan Puchalski <kajetan.puchalski@arm.com>
Signed-off-by: Peter Chen <peter.chen@cixtech.com>
Signed-off-by: Guomin Chen <Guomin.Chen@cixtech.com>
Signed-off-by: Gary Yang <gary.yang@cixtech.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>