dm: pmic: add s2mps11 PMIC I/O driver

This driver allows I/O operations on the Samsung S2MPS11 PMIC,
which provides lots of LDO/BUCK outputs.

To enable it, update defconfig with:
- CONFIG_PMIC_S2MPS11
and additional, if were not defined:
- CONFIG_CMD_PMIC
- CONFIG_ERRNO_STR

The binding info: doc/device-tree-bindings/pmic/s2mps11.txt

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/drivers/power/pmic/Makefile b/drivers/power/pmic/Makefile
index 00fde71..91e78f8 100644
--- a/drivers/power/pmic/Makefile
+++ b/drivers/power/pmic/Makefile
@@ -8,6 +8,7 @@
 obj-$(CONFIG_DM_PMIC) += pmic-uclass.o
 obj-$(CONFIG_DM_PMIC_MAX77686) += max77686.o
 obj-$(CONFIG_DM_PMIC_PFUZE100) += pfuze100.o
+obj-$(CONFIG_PMIC_S2MPS11) += s2mps11.o
 obj-$(CONFIG_DM_PMIC_SANDBOX) += sandbox.o i2c_pmic_emul.o
 obj-$(CONFIG_PMIC_ACT8846) += act8846.o
 obj-$(CONFIG_PMIC_TPS65090) += tps65090.o