power: regulator: s2mps11: add a regulator driver for s2mps11

exynos5422 has the s2mps11 PMIC.
s2mps11 pmic has the 10-BUCK and 38-LDO regulators.
Each IP and devices in exynos5422 can be controlled by each regulators.
This patch is support for s2mps11 regulator driver.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Anand Moon <linux.amoon@gmail.com>