regulator: mt6359: Add support for MT6359P regulator

The MT6359P is a eco version for MT6359 regulator.
We add support based on MT6359 regulator driver.

Signed-off-by: Hsin-Hsiung Wang <hsin-hsiung.wang@mediatek.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>