ram: stm32mp1: add driver

Add driver and binding for stm32mp1 ddr controller and phy

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index c4f10aa..e876c70 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -199,6 +199,7 @@
 M:	Patrick Delaunay <patrick.delaunay@st.com>
 S:	Maintained
 F:	arch/arm/mach-stm32mp
+F:	ram/stm32mp1
 
 ARM STM STV0991
 M:	Vikas Manocha <vikas.manocha@st.com>