Add initial dtsi file to support Hisilicon Hi6220 SoC with
support of Octal core CPUs in two clusters and each cluster
has quard Cortex-A53.

Also add dts file to support HiKey development board which
based on Hi6220 SoC.
Signed-off-by: Bintian Wang <bintian.wang@huawei.com>
Acked-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Reviewed-by: Yiping Xu <xuyiping@hisilicon.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Tested-by: Tyler Baker <tyler.baker@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>