regulator: hi6421: Add support to hi6421 regulators

Add support to hi6421 regulators. Hi6421 is a multi-functional PMIC
manufactured by HiSilicon Inc.

Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
Acked-by: Haojian Zhuang <haojian.zhuang@linaro.org>
4 files changed