arm64: dts: hikey960: add device node for pmic and regulators

add device node for hi6421 pmic core and hi6421v530
voltage regulator,include LDO(1,3,9,11,15,16)

Signed-off-by: Wang Xiaoyin <hw.wangxiaoyin@hisilicon.com>
Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>