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/drivers/ram/stm32mp1/Kconfig b/drivers/ram/stm32mp1/Kconfig
new file mode 100644
index 0000000..b9c8166
--- /dev/null
+++ b/drivers/ram/stm32mp1/Kconfig
@@ -0,0 +1,12 @@
+
+config STM32MP1_DDR
+	bool "STM32MP1 DDR driver"
+	depends on DM && OF_CONTROL && ARCH_STM32MP
+	select RAM
+	select SPL_RAM if SPL
+	default y
+	help
+		activate STM32MP1 DDR controller driver for STM32MP1 soc
+		family:	support for LPDDR2, LPDDR3 and DDR3
+		the SDRAM parameters for controleur and phy need to be provided
+		in device tree (computed by DDR tuning tools)