regulator: max77843: Add max77843 regulator driver

This patch adds new regulator driver to support max77843
MFD(Multi Function Device) chip`s regulators.
The Max77843 has two voltage regulators for USB safeout.

Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
Signed-off-by: Beomho Seo <beomho.seo@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>