stm32mp: regulator: add SoC pwr regulator support

This driver binds and manages the following regulator of
SoC's PWR block :
  - reg11
  - reg18
  - usb33

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/arch/arm/mach-stm32mp/Makefile b/arch/arm/mach-stm32mp/Makefile
index a9b523d..08ee642 100644
--- a/arch/arm/mach-stm32mp/Makefile
+++ b/arch/arm/mach-stm32mp/Makefile
@@ -9,3 +9,4 @@
 
 obj-$(CONFIG_SPL_BUILD) += spl.o
 obj-$(CONFIG_ARMV7_PSCI) += psci.o
+obj-$(CONFIG_$(SPL_)DM_REGULATOR) += pwr_regulator.o