regulator: hi655x: enable regulator for hi655x PMIC

Add the regulator driver for hi655x PMIC.

Signed-off-by: Chen Feng <puck.chen@hisilicon.com>
Signed-off-by: Fei Wang <w.f@huawei.com>
Signed-off-by: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Reviewed-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>