arm64: Enable Hisilicon ARMv8 SoC family in Kconfig and defconfig

This patch introduces ARCH_HISI to enable Hisilicon SoC family in
Kconfig and defconfig.

Signed-off-by: Bintian Wang <bintian.wang@huawei.com>
Acked-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Reviewed-by: Wei Xu <xuwei5@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>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>