power: regulator: stpmu1: Introduce stpmu1 driver

Enable support for the regulator functions of the STPMU1X PMIC. The
driver implements get/set api for the various BUCKS and LDOs supported
by the PMIC device. This driver is controlled by a device tree node
which includes voltage limits.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/power/regulator/Makefile b/drivers/power/regulator/Makefile
index f7873ad..d73a6e3 100644
--- a/drivers/power/regulator/Makefile
+++ b/drivers/power/regulator/Makefile
@@ -23,3 +23,4 @@
 obj-$(CONFIG_$(SPL_)DM_REGULATOR_LP873X) += lp873x_regulator.o
 obj-$(CONFIG_$(SPL_)DM_REGULATOR_LP87565) += lp87565_regulator.o
 obj-$(CONFIG_DM_REGULATOR_TPS65910) += tps65910_regulator.o
+obj-$(CONFIG_$(SPL_)DM_REGULATOR_STPMU1) += stpmu1.o